Tire contact patch test

The tyres of your car may seem imposing to you, as if solidly anchored into the ground, but in reality the contact with the road is very often no more than a few squared inches of rubber. Examining the tire patch on your jeep can indicate if your pressure is too high or low. The tire contact patch all vehicles are supported by a cushion of air contained in four flexible rubber tires. When this is the case the air pressure you come up with may very well be too low for highway service. A new developed test stand, which is capable of measuring the stresses in the contact patch of the rolling tire in all directions with a resolution of 1 mm, is described. Inch up is the process of mounting a lower aspect ratio tire and larger diameter wheel on your. Tire contact patch characterization through finite element modeling and. The large volume of air can support the load, but the low pressure causes the tire to become unstable. When you install wider tires without changing anything else, the size of the tires contact patch i.

Spin, longitudinal and side slip, the width effect. The local contact stresses of the investigated tread blocks are simulated by fea using the measured loading conditions of the smooth tire. The validated finite element model is then used for predicting the 3d stress distribution fields at the contact patch. In our opinion, you have to know the size of the contact patch your vehicle creates. These include ink measurements of footprint shape and groovevoid ratio, optical contact pressure measurement, and multiaxis measurements of footprint stress, motion, and frictional energy. The presentation is scheduled for wednesday, march 6th at 10. The fluid pressure was measured on an asphalt track for different speeds. The calculation of the composite slip shown in equation 7 should be modified because the tire contact patch length varies depending on the normal load. The force from the weight on the tire must be equaled by the tire in terms of pressure x area. Evaluation of tire tread and body interactions in the.

Roll the jeep over the paper to allow the tire to make an impression on the paper. Measuring contact patch shapes and their effect on tire performance at the 2019 tire technology conference in hannover, germany. Luna wil work with commercial partners and the air force to test the system and work towards a smooth transition to the fleet. With the tire at 35 psi paint two to three rows of tread. Aircraft tire contact patch force and shear sensor sbir. Analysis of tire contact parameters using visual processing. Speedo reading tire 1 is assumed accurate tire susp. To optimize the tire contact patch, smithers offers tire footprint stress and motion and footprint measurement testing. Good enough to know that if i wanted to go super low pressure sub 3 psi ground pressure id either halve my ground contact weight load from 240 to 120 pounds or. Furthermore, for the actual tire with carcass compliance, the spin torque will. Tire contact patch lowering pressure gain traction engine basics. Line up the paper on the floor, taping it down will keep it from moving or sticking to the tire. Estimation of vertical load on a tire from contact patch. If the tire pressure is held constant, the width of the tire can only change the shape of the contact patch.

Tire temperatures are the easiest and most costeffective link you have to the action at the tire contact patch. Internally, the contisportcontact 2 tire features continentals advanced mold contour amc, which allows the tires contact patch to become wider during braking to help shorten stopping distances. The tire contact patch, or tire footprint, is the area of the tire that directly connects the vehicle with the driving surface. Tire model in driving simulator university at buffalo. The predictive capabilities of the finite element tire model are also explored in order to predict the handling characteristics of the test tire under different maneuvers such as pure cornering and pure braking. We offer several options for realtime tire testing, including the new standard in tire testing, the dynamic contact force rig. Tires with a higher profile or aspect ratio that is, the height of the sidewall is fairly large compared to the width of the tire, tend to have a long and narrow contact patch. Wintertire treads have specifically engineered grooves, channels, and biting edges designed to dig into snow and push water away from the tires contact patch.

A set of algorithms was developed and used with the test data that were collected with both the trailer and the robot, and the contact patch length and the normal load were estimated. With over a decade of experience in the automotive testing industry, henning is wellversed in measuring, interpreting, and modeling tire. Each of these four small patches of rubber is known as the tire contact. Aaa allseason tire testing the primary purpose of the tire is to transmit acceleration and braking torque, generate cornering forces and provide dampening characteristics 2. Getting a grip examining the elements of tire traction. Even though the chalk test gave you a full tread contact patch, at a low pressure the tire may not be stable at highway speeds. An optical tire contact pressure test bench developed by the imma group is described.

The longer contact patch means that the tire deflection will be deeper, resulting in more internal friction and hysteresis within the tires layers. This is part 6 of my 10 part series on how race car tirestyres work. It differs for different types of tyres and sometimes under different road conditions. Truck tire types and road contact pressures by pedro yap senior design engineer.

Then an appropriate equation relating the patch length to the vertical load is used to calculate the load. The width of the contact patch has a considerable effect on the torque and indirectly on the side force because of the consumption of some of the friction by the longitudinal forces involved. Tire contact patch characterization through finite element. Citeseerx an optical tire contact pressure test bench. Best winter tires for safer snow driving car and driver. The test program was similar for each of the tires under investigation and consisted of visual processing of contact patches under the following conditions. The shape of a tires contact patch or footprint greatly influences its performance and is dependent.

These are the only points of contact between the vehicle and the road. Effect of tire pressure and type on response of flexible. A hell of a lot harder to calculate, but the resistance is about square inches contact patch times psi, not about pvnrt. In addition, the shape of the contact patch will influence the performance of the tire and the vehicle its mounted on. Since the tire is supporting the same load regardless, the contact patch will be bigger at lower pressures. Tuning tires tracking tire temperatures and tuning your. The contact patch is the only connection between the road and the vehicle. The system is based on the use of a laterally illuminated glass on which the tire leans. The tire contact patch length are calculated using following two equations. Tire contact patch characterization through finite. The acceleration signal was processed to obtain the contact patch length created by the tire on the road surface. The contact patch will vary in shape and size depending on the geometry of the tire, and this affects various performance characteristics of the tire. Since the wear characteristics of tires is a highly competitive area between tire.

The contisportcontact 2 features twin steel belts reinforced by nylon to stabilize the tread area to enhance handling, highspeed capability. Luna will apply its high density fiber optic strain sensing technology to a sensing mat that can resolve and isolate both normal and shear loading in the tire contact patch. The vertical load on a moving tire was estimated by using accelerometers attached to the inner liner of a tire. Avon did their tests at four different tire pressures for both tires. The design of the contact patch is an engineering feat that is specific not only to each manufacturer, but for each individual tire. The test bench allows performing normal pressure distribution and patch contact shape measurements on passenger car tires. That is a lot of force from those four tire contact patches.

Contact patch the risks due to under and over inflation. You want to preserve these few inches like the apple of your eyes, so stick to these few basic rules. In order to gain an insight into the processes in the tire contact area, a test setup was developed to directly measure the fluid pressure in the water film between tire and road. Vertical load is the load actually seen at the tire contact patch. The measurement system is based on the frustration of total internal reflection ftir of light.

The shape of a tires contact patch or footprint greatly influences its performance and is dependent on its profile or aspect ratio. Using the tire temperatures effectively can pay considerable dividends on the race track, and its worth the effort to learn what they mean and how to adjust setups accordingly. If you could place a car on a glass floor and look at it from below, you would see four patches of rubber, most folks are surprised at the size of these four patches, depending on the vehicle each patch is a little smaller than a hand. Tires with a higher profile or aspect ratio that is, the height of the sidewall is fairly large compared to the width of. Almost all tire manufacturers make a tire in this category. Estimation of the tire contact patch length and normal. Roll it with moderate force, ensuring that you contact every part of the patch. Wheel energy measured a 75millimeterlong footprint for a 700 x 23 tire inflated to 112. How to put a patch on a punctured tire yourmechanic advice. The contact patch of a tyre is the section of the tyres tread that is in physical contact with the road surface. So, if the literal contact patch is all that matters, then a 3mm allen wrench will take 17 the force to deform a tire a certain distance than an 8mm allen wrench will. The contact patch of most tires is about the size of your hand and has to handle a lot more weight and force than those big reeboks do.

For a common passenger car, the area of all four tires in contact with the ground is roughly the size of an 8. The maximum width of the contact patch or footprint is determined by the tires tread width. This approach uses the tire test bench with the set of contact patch monitoring based on image processing procedures. Pacejka, in tire and vehicle dynamics third edition, 2012. Given this alone, the contact patch area should be constant for a given tire pressure and load.

This part covers the dynamics of a tires contact patch. Smithers has the tools and expertise to help engineers understand and optimize the tire contact patch. The size and shape of the contact patch, as well as the pressure distribution within the contact patch, are important to the ride qualities and handling characteristics of a vehicle. Also, the friction potential between the tire and the road was evaluated using a small ground robot.

For high performance driving, the tires contact patch would. Tire contact patch lowering pressure gain traction. Dynamic measurement of the fluid pressure in the tire. Using the chalk method for determining psi interco tire. The main goal of this study was the experimental investigation of the fluid pressure in the boundary region between wet grip and hydroplaning.

The veloflex master 25 mm deserves our coveted best value tip. This new technology provides a unique opportunity to the customer by measuring the dynamic tire patch shape with a 6component force transducer embedded into a 3. By chalking your tires and finding the correct psi to get a full contact patch you get better performance out of them and more wear out of your very expensive tires. With the combination patch all the way in place, seat the patch in the rubber cement with a roller. Using some paper and paint we test the patch on our cj. This includes the weight resting on the tire contact patch plus any aerodynamic downforce.

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