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Published information on studies of something so critical to safety as passenger vehicle tire pressures can be found [1, 2]; however, they only account for rolling tires. Studies related to spare tire pressures are lacking. This paper is the result of measurements on 150+ vehicles and the most surprising results are presented regarding the influence of Tire Pressure Monitoring Systems (TPMS) and the new spare tire locations and use. A statistical study was performed on the collected data to determine the correlation between tire pressures, vehicle age and TPMS. One particular topic of investigation was the relationship between various factors that influence spare tire pressure. Some newer models, particularly some mini-vans, have placed the spare tire in an unusual and inconvenient place for regular maintenance. Based on the data collected, TPMS has a positive influence on rolling tires but not on spare tires. The results support the need for TPMS to also monitor spare tire pressures. Language: en

To quantify the fuel economy (FE) effect of some common vehicle accessories or alterations, a compact passenger sedan and a sport utility vehicle (SUV) were subjected to SAE J2263 coastdown procedures. Coastdowns were conducted with low tire pressure, all windows open, with a roof top or hitch-mounted cargo carrier, and with the SUV pulling an enclosed cargo trailer. From these coastdowns, vehicle dynamometer coefficients were developed which enabled the execution of vehicle dynamometer experiments to determine the effect of these changes on vehicle FE and emissions over standard drive cycles and at steady highway speeds. The FE penalty associated with the rooftop cargo box mounted on the compact sedan was as high as 25-27% at higher speeds, where the aerodynamic drag is most pronounced. For both vehicles, use of a hitch mounted cargo tray carrying a similar load resulted in very small FE penalties, unlike the rooftop cargo box. The results for the SUV pulling a 3500 pound enclosed cargo trailer were rather dramatic, resulting in FE penalties ranging from 30%, for the city cycle, to 50% at 80 mph, at which point significant CO generation indicated protective enrichment due to high load. Low tire pressure cases resulted in negligiblemore » to 10% FE penalty depending on the specific case and test point. Driving with all four windows open decreased FE by 4-8.5% for the compact sedan, and 1-4% for the SUV.« less

Today the stresses in rotating suspension components under physical load conditions are calculated with assumed distributions of contact forces between tire and wheel since the true distributions are not known. This causes uncertainties in the fatigue evaluation and requires an experimental verification of the attained results. The paper describes how the desired force distributions are identified from strains measured on wheels while rolling under load. On the one hand the purpose is to find out how the wheel loads, the tire pressure and tire parameters, e.g. the tire height influence the load transfer between tire and wheel, and on the other hand to derive distributions of the contact forces for reliable stress calculations. To verify the results, identified force distributions are applied to calculate strains, which are compared to measured strains.

Sensor fusion is a signal processing discipline wherein one tries to merge – or fuse – sensor data information coming from different physical sensors. In this paper we illustrate how sensor fusion can be used to design a low tire pressure warning system using existing sensors on a modern vehicle. Results from real-world tests on a car are given as illustration of the method’s feasibility.

The idea of a virtual sensor is to extract information of parameters that cannot be measured directly, or at least would require very costly sensors, by only using available information. Virtual sensors are described for the friction between road and tire, the tire inflation pressure and wheel imbalance. There are certain interconnections between these virtual sensors so they are preferably implemented in one unit. Results from a real-time implementation, using mainly sensor information from the CAN bus, are given.

Under inflated or deflated tires are known to cause increased forward drag and lateral steering effects on vehicles. This paper documents the results of a series of tests conducted to determine the magnitude and effects of under inflated or deflated tires on cars and light trucks. The first phase of the tests involved the measurement of forward deceleration rates during a series of coast to stop tests with all of the vehicle tires initially inflated to the rated pressure. This was followed by tests at various under inflation pressures. As anticipated all vehicles experienced an increase in the coast to stop deceleration rates at under inflated tire pressure conditions. However, the increase in the deceleration rates were not dramatic in magnitude. The second phase of the tests involved coast to stop tests and lateral motion tests with totally deflated tires in order to simulate a tire blow-out condition. The tests provided consistent results within the test speed ranges up to 45 mph. The results may not be similar at higher speeds and the results should not be randomly extrapolated to higher vehicle speeds without a valid basis. If higher speed affects are desired, the same test methodology is considered to be a reasonable approach to gather data. (A) For the covering abstract of the conference see IRRD 899758.

There has been considerable experimental research of cars crashing into roadside curbs. This paper uses all the published information to establish a relationship to estimate the ability of a curb to safely redirect a vehicle. A curb's ability to redirect a vehicle depends upon the speed and angle of impact, the surface material, if it is wet or dry and the radius of the impacting tire. There are other factors such as the aggressiveness of the tire tread and the tire pressure that are thought to be important but have not been incorporated into the analytical procedure. The equations may be used in accident reconstruction to estimate a minimum vehicle's speed to mount a curb. (A) For the covering abstract of the conference see IRRD 899758.

Tires built from compounds with equal storage moduli but different loss moduli for tread and body were subjected to designed tests on both roadwheel and twin rolls. The results allowed computation of the tread contribution to the total rolling loss, at various loads and pressures. On twin rolls, the relative tread contribution was much higher than it was on the roadwheel (typically, 60% vs 30%). On both machines, the loss contribution of the tread depended strongly on its loss modulus and on tire load; the effect of inflation pressure was small.

This paper describes two types of tire pressure warning devices, TWD-I and TWD-II, that are low in cost and are easy to install on a vehicle. TWD-I has a buzzer and a dry-cell battery that are attached on the inside of the wheel center cap. They are connected to a pressure switch that is attached to the air valve stem after the tire is filled with air to the prescribed pressure. If the pressure drops below a certain level, the switch sends a signal that energizes buzzer. TWD-II is a kind of monitor that indicates a drop in tire pressure by changing the color of the wheel center cap through the action of a diaphragm and a magnet. In comparison with conventional innovations, the two new warning devices offer the advantages of lower cost and easier installation on vehicle.

Fuel economy data developed as a result of two series of automobile tests were compared and discussed. The tests were performed in 1973 and 1979, on representative samples of 1969-73 and 1979-80 model year automobiles respectively. Fuel economy of the test autos was determined under the following conditions: constant speed, the effect of air conditioning, open windows, tire pressure, acceleration rate, and on-the-road tests involving freeway, light city and heavy city driving.

This paper presents information on the condition, accuracy, and repeatability of automotive service equipment in use. This information was derived from on-site data obtained at a national sample of 307 auto repair/diagnostic facilities. Over 6000 pieces of some 24 types of equipment, ranging from tire pressure gages to computerized engine analyzers, were subjected to a detailed field engineering evaluation.

The effect of inflation pressure on rolling resistance, tread wear, traction, bruise resistance and mechanical properties of bias, bias-belted and radial tires has been investigated. Inflation pressures from 16 to 48 psi (110 to 330 kPa) were used. At various test conditions radial tire rolling resistance was found to be 12-60% lower compared to the bias and bias-belted tires. The rate of rolling resistance reduction with increasing pressure diminishes and levels off at pressures above 40 psi (275 kPa). Treadlife increases with higher inflation pressures, but results in a disproportionate center wear condition on both bias and bias-belted constructions. Pressure variations had little or no effect on traction. However, changes in cornering coefficient and aligning torque at higher inflation pressures will require tire/vehicle adjustments to achieve desired handling characteristics.

Previous limited tire pressure surveys have suggested that the tire pressures on Canadian vehicles are critically low and could be resulting in an abnormally high number of tire failures. Many tires examined by Transport Canada as a result of complaints of alleged safety defects were found to have failed as a result of underinflation. In December, 1978, Transport Canada initiated a national tire maintenance survey that was designed to: obtain a nationally representative sample of tire pressures to determine whether out-of-limits pressures were a serious problem; record driver maintenance habits and characteristics and attempt to relate these to tire pressures (the strength of these relationships could suggest potential countermeasures if a tire pressure problem existed); and obtain cursory information on the number and types of tire failures that have occured over the last three years. The survey data were obtained from interviews with 745 householders selected at random from across the country. The data obtained from each interview included the sex and age of each driver, the physical properties of the tires on his or her vehicle, the reported vehicle and tire maintenance habits of each driver, and the number and types of tire failures that he or she may have experienced in the past. (Author)