Increase In Inflation Pressure Research Articles

Measurement of the lateral characteristics and identification of the Magic Formula parameters of city and cargo bicycle tyres

The paper presents measurements of the lateral force and self-aligning torque from cargo and city bicycle tyres. Based on the experimental data, we have determined the parameters for the Magic Formula model, for lateral force and self-aligning torque. We performed tests with VeTyT, an indoor test rig specific for bicycle tyres, under different vertical loads (ranging from 343 N to 526 N), camber angles (−5, 0, 5) deg and inflation pressure (from 300 kPa to 500 kPa). For each condition, we evaluated the cornering stiffness and found that it generally decreases with the increase in inflation pressure for the tour/city bicycle tyres. However, the cargo tyre tested showed an opposite trend, with an increase in the cornering stiffness as the inflation pressure increased from 300 kPa to 400 kPa.

Fabrication and Characterization of Pneumatic Unit Cell Actuators

In the realm of virtual and augmented reality (VR/AR) and teleoperation applications, haptic feedback plays a role in enhancing task performance. One of the main goals of this study is to simplify haptic device hardware while improving its capacity to provide various stimuli at different intensities. In response to these challenges, this research introduces the Pneumatic Unit Cell (PUC), a soft pneumatically driven device—a hollow silicone cylinder with the ability to provide both static-pressure and vibrotactile feedback. Furthermore, the Pneumatic Unit Cell’s design simplicity has the potential for scalability, modularity, and the flexibility to mount the device on any part of the human body. The focus of the current paper is to study PUCs as actuators and lay the foundation for future perceptual studies. The characterization studies encompass the fabrication and verification of the fabrication accuracy through dimensional measurements, characterizing PUCs under static-pressure conditions (measuring the free deflection and blocking force) and frequency conditions (measuring the free deflection). In the static-pressure conditions, we applied pressures ranging from 0 to 40 kPa to measure the free deflection and from 0 to 30 kPa to measure the blocking force. In the frequency conditions, we applied pressures of 10, 20, and 30 kPa with inflation/deflation rates varying between 0.5 Hz and 100 Hz. The measurements of free deflection under static-pressure conditions revealed that 0.9 mm and 1.2 mm PUCs exhibit a linear increase in free deflection with an increase in inflation pressure. The results of free-deflection measurements under the frequency conditions indicate a direct relationship between the free-deflection magnitude and applied pressure. The results also demonstrate an inverse relationship to the frequency of inflation/deflation. The characterization results demonstrate a broad range of free deflection observed under both static-pressure and frequency conditions, encouraging the potential application of Pneumatic Unit Cell actuators as haptic devices.

Load-sharing characteristics of stenting and post-dilation in heavily calcified coronary artery

In this work, stenting in non-calcified and heavily calcified coronary arteries was quantified in terms of diameter-pressure relationships and load transfer from the balloon to the artery. The efficacy of post-dilation in non-calcified and heavily calcified coronary arteries was also characterized in terms of load sharing and the changes in tissue mechanics. Our results have shown that stent expansion exhibits a cylindrical shape in non-calcified lesions, while it exhibits a dog bone shape in heavily calcified lesions. Load-sharing analysis has shown that only a small portion of the pressure load (1.4 N, 0.8% of total pressure load) was transferred to the non-calcified lesion, while a large amount of the pressure load (19 N, 12%) was transferred to the heavily calcified lesion. In addition, the increasing inflation pressure (from 10 to 20 atm) can effectively increase the minimal lumen diameter (from 1.48 to 2.82 mm) of the heavily calcified lesion, the stress (from 1.5 to 8.4 MPa) and the strain energy in the calcification (1.77 mJ to 26.5 mJ), which are associated with the potential of calcification fracture. Results indicated that increasing inflation pressure can be an effective way to improve the stent expansion if a dog bone shape of the stenting profile is observed. Considering the risk of a balloon burst, our results support the design and application of the high-pressure balloon for post-dilation. This work also sheds some light on the stent design and choice of stent materials for improving the stent expansion at the dog bone region and mitigating stresses on arterial tissues.

Numerical Simulation of Grounding Characteristics and Temperature Field of Mine Tires under Multiple Working Conditions

Mine tires are an essential and expensive component of heavy mining machinery. This study explored the grounding characteristics and temperature field distribution of mining tires during driving as well as the relationships between the maximum temperature and tire inflation pressure, load, and speed. Two-dimensional and three-dimensional finite element models of mine tires were established. Steady-state rolling simulation analysis was conducted based on inflation and static load simulations. Temperature field simulation analysis was conducted with the tire section as a research object. The accuracy of the finite element model was verified. Analysis results demonstrated that the grounding contact area decreased with an increase in charging pressure and increased with an increase in load. With an increase in inflation pressure, the maximum normal grounding stress increased in the middle part of the tread and decreased near the shoulder. The maximum normal grounding stress continuously deviated in the shoulder direction with an increase in load. Temperature field analysis indicated that the tire had the maximum temperature at the binder position, where the first belt layer was connected to the second belt layer, which corresponds to the maximum stress position in the steady-state rolling simulations. Tire temperature increased with driving speed. The maximum temperature increased with an increase in tire deflection, whereas the deflection decreased with an increase in inflation pressure and increased with an increase in load. Speed had the greatest influence on the maximum temperature, followed by load, with inflation pressure having the smallest influence. The results of this research can be used to improve the service life of mine tires to improve productivity and reduce costs.

Experimental and Numerical Studies on the Inflatable Recyclable Anchor in the Tube Piece Type Based on the Soil-Anchor Interaction Mechanism

This paper deeply studies the characteristics and “uplift bearing capacity” of a novel type of inflatable recyclable anchor in the tube piece. The proposed novel inflatable recyclable anchor in the tube piece type comprises a metallic rod, an inflatable anchorage device, and a recovery device. Fifteen field uplift tests are conducted to investigate the effects of inflation pressure, thickness of the steel disc, embedment length, and time lapse between anchor inflation and pullout on “the uplift bearing capacity.” The results show that “the uplift bearing capacity” of the novel inflatable anchor in the tube piece type increases with the increase of inflation pressure, thickness of the steel disc, and embedment length. With the increase of inflation time, “the uplift bearing capacity” of the novel inflatable anchor experiences an increase after first experiencing a decrease. The finite element analysis method is used to establish a numerical analysis model of the inflatable anchor, and the distribution law of the tensile stress of the surrounding soil during the pullout of the anchor is analysed. Compared with the traditional grouted anchor, the proposed anchor has an obvious superiority in recyclability, reusability, and swifter formation of anchorage force and thus is a resource-saving and environmentally friendly anchor technology.

Reinforcement of the anchor balloon system in percutaneous coronary intervention: an in vitro assessment

We evaluated the factors that increase the maximum static friction force between the anchoring balloon and the vessel wall. The anchor technique in percutaneous coronary intervention (PCI) may be better supported by a guiding catheter. However, in some cases, the anchor balloon does not perform optimally due to slippage within the anchoring vessel. Furthermore, the optimal procedure for balloon anchoring remains unknown. We evaluated the maximum static friction force of the anchor balloon via in vitro assessments using a simulated vessel model and coronary balloons. The simulated vessel model was composed of polytetrafluoroethylene, and its inner diameter was 1.5mm. The various-sized balloons (diameter: 1.5mm, 1.75mm, and 2.0mm; length: 10mm and 15mm) were inflated within the simulated vessel at various atmospheres. The maximum static friction force was measured by pulling on the balloon catheter shaft using 10-g weights. We performed the same experiment with a jailing 0.014″ wire under the anchoring balloon. Evaluated wires included a silicon coating coil wire, hydrophilic coating coil wire, polymer-coated non-tapering wire, and polymer-coated tapered wire. The maximum static friction force between the anchoring balloon and the simulated vessel increased with an increase in inflation pressure and balloon length. However, increasing the balloon diameter was not effective. The jailing 0.014″ wire, particularly coil wire, was effective in increasing the maximum static friction force of the anchor balloon. A longer balloon, higher inflation pressure, and jailing coil wire could reinforce the anchor balloon system.

Experimental study on compaction effects on the ballistic resistance of sandbags

An experimental study was conducted to find out the effects of compaction of sand on the ballistic resistance of the sandbag. The implementation of various sandbag fabrics, namely, polyethylene, polypropylene, polyvinylchloride and Twaron, was also investigated. The sandbags were tested under various configurations - uncompacted, manually compacted, vacuum compacted and pneumatically compacted by inserting an inflatable airbag into the sandbag. Depending on their fabric strength, the sandbags were pneumatically compacted or pressurized up to different inflation pressures. Burlap, polyethylene and polypropylene sandbags were tested at 0.5 bar and polyvinyl sandbags at 0.5 and 1.0 bars while Twaron sandbags were tested at 0.5, 1.0 and 2.0 bars. All sandbag specimens were subjected to ballistic impact by a spherical steel projectile. The increase in inflation pressure led to the rise in shear resistance of the sand through compaction and the rise in fabric pretension as well, resulting in better ballistic resistances (higher ballistic limit and energy absorbed) of the sandbag specimens. With the aid of inflatable airbags, it is possible for sandbags of less expensive and lower strength fabrics to exceed the ballistic resistances of uncompacted and manually compacted high performance Twaron sandbags.

Structural behaviour of inflatable PVC fabric cylindrical tubes

Inflatable structures are light weight structures that have often been proposed for aerospace applications. They are light in weight, easily manufacturable and foldable. Thus, they can be easily transported and deployed in space. However, the proper characterization for their properties of these structures is still missing.The work done in this paper aims at studying the structural properties of inflatable cylindrical tubes, manufactured from PVC fabric. The cylindrical tubes are fixed as cantilever beams and subjected to a load at the beam tip. Samples of different sizes are tested under different inflation pressures and loads. Load-deflection curves are recorded for each test. Results show that the beam stiffness increases with the increase of inflation pressure and beam cross sectional area. The inflatable beams show linear behaviour up to a certain critical load at which wrinkling occurs. Beyond this load the behaviour of the beam becomes nonlinear and can be unstable. Hysteresis phenomenon is also observed during the unloading of the beam. In addition, Free vibration analysis was conducted to study the effect of inflation pressure on the beam natural frequency. This work is a part of project aiming to design and manufacture an inflatable wind turbine blade to overcome the drawbacks of conventional blades.

Development of a New Inflatable Controlled Anchor System and Experimental Study of pull-out Capacity

Considering the deficiency of traditional anchors, we propose a new type of inflatable controlled anchor system in this paper. The working mechanism and its structural composition of newly designed inflatable controlled device are discussed in detail. To investigate the performance and pull-out capacity of this new anchor system, a series of field tests were carried out under different inflation pressure conditions. By comparing these test results with those of traditional grouting anchors, a full-process constitutive model of anchor-soil interface is proposed to depict the pull-out characteristics of the inflatable controlled anchor. The results show that the ultimate bearing capacity of the inflatable controlled anchor is greater than that of the traditional grouting anchor when the inflation pressure is greater than 0.2 MPa and the ultimate bearing capacity of this new anchor improves obviously with the increase of inflation pressure. When the inflation pressure reaches 0.4 MPa, the ultimate bearing capacity of the inflatable controlled anchor is 2.08 times that of the traditional grouting anchor. Through comparison with the experimental curves, the results of model calculation indicate that the proposed anchor-soil interface constitutive equation can describe the pull-out characteristics of the inflatable controlled anchor. The designed controlled anchor has the advantages of no grouting, recyclability, rapid formation of anchoring force, and adjustable anchoring force.

Development of a Single Wheel Test Rig for Measuring Motion Resistance

Research on soil-wheel interaction is essential in studies of motion resistance of narrow wheels of agricultural machines. The aim of this research was to study the effects of soil moisture content and tyre inflation pressure on motion resistance of narrow wheels using a locally developed single wheel test rig. A single wheel Test Rig facility was developed at Federal University of Technology, Akure. It consists of a soil bin, carriage, single narrow wheel tester, trolley and drive system. An existing indoor soil bin facility was equipped with a soil bin which dimension was 9.76 m length x 1.98 m width x 0.92 m high. The single-wheel test facility was utilized to investigate the effect of tyre inflation pressure and vertical load on motion resistance of wheel. Two narrow wheels of 90/10-10 in width, IRC MB90 tyre were used as the test wheels on clay soil and were separately installed on a carriage that traversed the length of soil bin. Two inflation pressures of 274 kPa and 380 kPa and four levels of vertical load applied on wheel (i.e. 15, 20, 30, and 40 kg) were examined at two different soil moisture conditions (bulk density of 1.58 g/cm3 and 1.55 g/cm3, soil moisture content of 8% and 10% dry basis and soil penetration resistance of 1.02 MPa and 1.5 MPa). Exponential regression was obtained for the two wheels to check for linearity at different moisture content, R2 value for test wheel 1 with inflation pressure of 270 kPa at 8% moisture content was 0.9974 while that of inflation pressure of 380 kPa at 10% moisture content was 0.9952; also for test wheel two (2) R2 value was 0.9977 and 0.9914 at moisture content of 8% and 10% respectively, this shows for test wheel 1 with inflation pressure of 270 kPa at 8% moisture content showed more motion resistance compared to motion resistance of test wheel 1 at inflation pressure of 380 kPa and 10% moisture content, while for test wheel 2 with inflation pressure of 270 kPa showed low motion resistance at 8% motion content. The effect of different inflation pressures and vertical loads on the motion resistance of the narrow wheels has been investigated under different moisture content (8% and 10%). The contact area for all tests was in the range of 309-330 cm2, average contact pressure increased nearly linearly with increase in vertical load and increase in inflation pressure The research provides data that are relevant in the study of soil-wheel interaction.

Experimental Study of an Inflatable Recyclable Anchor

This paper describes an investigation into the performance and pullout capacity of a new inflatable anchor system embedded in deep excavation engineering. The proposed inflatable recyclable anchor system consists of a rubber pneumatic bag, movable steel plate, and force transmission bar, which can all be recycled after use. By conducting a number of field pullout tests, it is found that the pullout bearing capacity of the proposed anchor is related to the inflation pressure, the length of the rubber pneumatic bag, and the embedment depth. It is found that, with the exponential increase of inflation pressure or length of the rubber pneumatic bag, the pullout bearing capacity of the novel inflatable anchor increases exponentially. The proposed inflatable recyclable anchor can meet the bearing requirements of traditional grouted anchors. Moreover, the proposed anchor not only has better supporting effects than traditional grouted ones, but it also has the advantages of recyclability, repeated use, and rapid formation of anchorage force. It is a new green and low-carbon anchorage, so it will have good application prospects in temporary foundation pit slope engineering.

Effects of Some Properties of Drive Tires Used in Horticultural Tractors on Tractive Performance

Many studies on tractive performance of tractor tires have been carried out to solve soil-wheel interaction problems in the last decades. The purpose of this study is to experimentally determine effects on tractive performance of radial and bias-ply drive tires at three different tire lug heights, axle loads and inflation pressures. The experiments were carried out in stubble field conditions. To obtain sufficient performance data, a new single wheel tester was designed and manufactured. Travel reduction, net traction ratio and tractive efficiency varied from 3.3% to 34.1%, 0.24 to 0.93 and from 0.27 to 0.78 respectively depending on drawbar pull. The effects of tire type, lug height, dynamic axle load and inflation pressure on tractive efficiency were found significant (P<0.01) by the performed variance analysis and LSD tests. Radial tires provide better tractive performance compared with bias-ply tires. The tractive efficiency increased especially with increasing dynamic axle load and decreased with increasing tire inflation pressure. Tire dynamic axle load was the major contributory factor on tractive performance as compared with other independent variables. For a given drawbar pull, it was observed that tractive efficiency of radial tire can be maximized by selecting appropriate levels of lug height, dynamic axle load and inflation pressure.

A theoretical model for the tread slip and the effective rolling radius of the tyres in free rolling

A rigid–elastic coupling theory for the rolling kinematics of tyres, by which the tread slip, the effective rolling radius and the ply steering of the tyres can be analysed, was formulated. The theory demonstrates that, during free-rolling motion, the coupling between the rotational velocity Ω along the wheel axis and the circumferential displacement gradient generates the longitudinal tread slip, and the coupling between the rotational velocity Ω along the wheel axis and the lateral displacement gradient generates the lateral tread slip and the ply steering. Revisiting the tread slip phenomenon using the newly proposed method numerically proves the kinematic mechanism of the rolling friction. It can be found that the effective rolling radius Re increases with increasing inflation pressure and decreases with increasing load; the sensitivity of Re to the inflation pressure is greater than the sensitivity of Re to the load. The good agreement between the theoretical predictions and the test results for the effective rolling radius of the radial tyres of a car is found. The coupling of the displacement gradient and the rigid rolling kinematics causes non-symmetry of the lateral tread slip which, in turn, leads to the ply steering and the residual aligning moment; these depend on the belt and tread design. The proposed theory and approach provide a quick and powerful tool for analysing the tread slip, the effective rolling radius and the ply steering of the tyres under free rolling.

Experimental Determination of Inflatable, Braided Tube Constitutive Properties

AbstractThe primary objective of this study was to conduct constitutive tests of relatively large diameter inflatable, braided fabric tubes at different inflation pressures and braid angles in order to quantify the longitudinal modulus, in‐plane shear modulus and effective lamina stiffness properties. The stiffness properties quantified here are of high interest because the same braided fabric tubes have been used in the construction of test articles for a major, multi‐year, ground based test campaign led by the United States National Aeronautics and Space Administration. These properties are also input directly into high‐fidelity yet computationally intensive 3D shell‐based finite‐element simulations of the large, inflatable structures. Experimental methods employed during this study included tension–torsion testing, uniaxial tension testing of individual fibre tows, and uniaxial tension testing of gas bladder coupons. Digital image correlation was used to measure all of the geometric information that is necessary to perform netting theory calculations. The test results indicate that fabric in‐plane shear modulus is highly dependent on both braid angle and inflation pressure, but that longitudinal stiffness is quite small and relatively unaffected by braid angle and pressure. In addition to advancing the state‐of‐the art in experimental constitutive property determination of inflatable, braided fabric, this study includes the development of a method to back calculate lamina properties from the experimental results that are suitable for use as input to commonly used finite‐element programmes. The digital image correlation data revealed spatial variation of shear strain that was important to consider when computing the gross shear stiffness. Digital image correlation data also captured the braid surface flattening with increasing inflation pressure, which supports the fibre de‐crimping theory.

Volume Guarantee Ventilation during Surgical Closure of Patent Ductus Arteriosus

Surgical closure of patent ductus arteriosus (PDA) is associated with adverse outcomes. Surgical exposure requires retraction of the lung, resulting in decreased aeration and compliance. Optimal respiratory support for PDA surgery is unknown. Experience with volume guarantee (VG) ventilation at our institution led us to hypothesize that surgery would be better tolerated with automatic adjustment of pressure by VG to maintain tidal volume (VT) during retraction. The objective of this study was to describe ventilator support, VT, and oxygenation of infants supported with VG during PDA surgery. Ventilator variables, oxygen saturation, and heart rate were recorded during PDA surgery in a convenience sample of infants during PDA closure on VG. Pressure limit increased 11% and set VT was 26% lower during lung retraction. Fentanyl and pancuronium/vecuronium were used for anesthesia/muscle relaxation. Longitudinal data were analyzed by analysis of variance for repeated measures. Seven infants, 25.4 ± 1.5 weeks and 723 ± 141 g, underwent closure of PDA on VG at a mean age 29.9 days. No air leak, bradycardia, or death occurred. Target VT was maintained with a modest increase in inflation pressure. Oxygenation remained adequate. VG avoided hypoxemia and maintained adequate VT with only a modest increase in peak inflation pressure and thus may be a useful mode during PDA surgery.

Study of Cornering Maneuvers of a Pneumatic Tire on Asphalt Pavement Surfaces Using the Finite Element Method

Field experience shows that most road accidents that occur during turning maneuvers are caused by the loss of vehicle control. The loss of vehicle control is often related to a lack of sufficient friction between the tire and the pavement surface. In experiments and analytical studies, the overall antiskidding performance of a pneumatic tire has been observed to be affected by operating conditions, road texture, and surrounding temperatures. Interactions of these parameters create a complex relationship between their combined effect and the tire's ability to combat skidding. One way to analyze the cornering maneuvers of a vehicle is by means of a validated finite element tool that can carry both the tire and the pavement properties. Few computational studies have been conducted to study the cornering performance of a rolling pneumatic tire, and none of these studies included the role of pavement surface morphologies in their analysis. In this study, a thermomechanical framework was used to analyze the influence of temperature on cornering friction. The cornering friction coefficient was found to decrease with an increase in the loads and the speeds. The cornering friction coefficient was found to increase with an increase in inflation pressure, sideslip angle, and pavement surface texture depth. The proposed study contributes to an understanding of the cornering performance of passenger car tires.

Artificial Neural Network estimation of wheel rolling resistance in clay loam soil

Despite of complex and nonlinear relationships imparting soil–wheel interactions, however, logical, non-randomized, and manifold relations tackle to express and model the interactions which are valid for variety of conditions and are likely to be established whereas mathematical equations are restricted to present. A 3-10-1 feed-forward Artificial Neural Network (ANN) with back propagation (BP) learning algorithm was utilized to estimate the rolling resistance of wheel as affected by velocity, tire inflation pressure, and normal load acting on wheel inside the soil bin facility creating controlled condition for test run. The model represented mean squared error MSE of 0.0257 and predicted relative error values with less than 10% and high coefficient of determination (R2) equal to 0.9322 utilizing experimental output data obtained from single-wheel tester of soil bin facility. These rewarding outcomes signify the fitting exploit of ANN for prediction of rolling resistance as a practical model with high accuracy in clay loam soil. Derived data revealed rolling resistance is less affected by applicable velocities of tractors in farmlands nevertheless is much influenced by inflation pressure and vertical load. An approximate constant relationship existed between velocity and rolling resistance implying that rolling resistance is not function of velocity chiefly in lower ones. Increase of inflation pressure results in decrease of rolling resistance while increase of vertical load brings about increase of rolling resistance which was measured to be function of vertical load by polynomial with order of two model validated by conventional models such as Wismer and Luth model.

Investigating the effect of velocity, inflation pressure, and vertical load on rolling resistance of a radial ply tire

A single-wheel tester facility at Department of Agricultural Machinery of Urmia University was utilized to investigate the effect of velocity, tire inflation pressure, and vertical load on rolling resistance of wheel. A Good year 9.5L-14, 6 radial ply tire was used as the tester wheel on clay-loam soil and was installed on a carriage traversing the length of soil bin. Three inflation pressures of 100, 200, and 300kPa as well as three levels of velocity (i.e. 0.7, 1.4, and 2m/s) and five levels of vertical load applied on wheel (i.e. 1, 2, 3, 4, and 5kN) were examined. Covariance analysis (ANCOVA) of resulted data revealed that rolling resistance is less effected by applicable velocities of tractors in farmlands but is much influenced by inflation pressure and vertical load. An approximate constant relationship existed between velocity and rolling resistance indicating that rolling resistance is not a function of velocity particularly in lower ones. Moreover, it was observed that increase of inflation pressure results in decrease of rolling resistance. Additionally, increase of vertical load brings about increase of rolling resistance which was estimated to have polynomial relation with order of two. A model comprising tested variables was developed with relative high accuracy.

Analysis of Regional Mechanics in Canine Lung Injury Using Forced Oscillations and 3D Image Registration

Acute lung injury is characterized by heterogeneity of regional mechanical properties, which is thought to be correlated with disease severity. The feasibility of using respiratory input impedance (Z rs) and computed tomographic (CT) image registration for assessing parenchymal mechanical heterogeneity was evaluated. In six dogs, measurements of Z rs before and after oleic acid injury at various distending pressures were obtained, followed by whole lung CT scans. Each Z rs spectrum was fit with a model incorporating variable distributions of regional compliances. CT image pairs at different inflation pressures were matched using an image registration algorithm, from which distributions of regional compliances from the resulting anatomic deformation fields were computed. Under baseline conditions, average model compliance decreased with increasing inflation pressure, reflecting parenchymal stiffening. After lung injury, these average compliances decreased at each pressure, indicating derecruitment, alveolar flooding, or alterations in intrinsic tissue elastance. However, average compliance did not change as inflation pressure increased, consistent with simultaneous recruitment and strain stiffening. Image registration revealed peaked distributions of regional compliances, and that small portions of the lung might undergo relative compression during inflation. The authors conclude that assessments of lung function using Z rs combined with the structural alterations inferred from image registration provide unique but complementary information on the mechanical derangements associated with lung injury.

Tractor tire aspect ratio effects on soil bulk density and cone index

A 580/70R38 tractor drive tire with an aspect ratio of 0.756 and a 650/75R32 tire with an aspect ratio of 0.804 were operated at two dynamic loads and two inflation pressures on a sandy loam and a clay loam with loose soil above a hardpan. Soil bulk density and cone index were measured just above the hardpan beneath the centerline and edge of the tires. The bulk densities were essentially equal for the two tires and cone indices were also essentially equal for the two tires. Soil bulk density and cone index increased with increasing dynamic load at constant inflation pressure, and with increasing inflation pressure at constant dynamic load. In comparisons of the centerline and edge locations, soil bulk density and cone index were significantly less beneath the edge than beneath the centerline of the tires. Soil compaction is not likely to be affected by the aspect ratio of radial-ply tractor drive tires when aspect ratios are between 0.75 and 0.80.