How Tyres Support Your Vehicle
Looking at your vehicle with its new cheap online tyres that you have had fitted it’s amazing to fathom how those tyres with approximately 30 pounds per square inch (psi) can support your car. If you look at your tyres closely you will see they are not actually as round as you thought and there is a flat spot at the bottom where the tyre meets the road. This flat spot is known as the contact patch.
Imagine looking up at your vehicle through a glass road. This contact patch could be measured simply by multiplying the length of the contact patch by its width to work out the area, then adding all four areas.The weight of your car could be estimated by measuring each contact patch of each tyre, adding them together, then multiplying the sum by the tyre pressure!
Here’s some maths to illustrate: an average 2 tonne car’s contact patch is about equal to its weight divided by the tyres pressure, for example 2 tons divided by 30 pounds per square inch equals 133 square inches. With your car tyres being around 7 inches wide the contact patch for each tyre is approximately 4.75 inches long.
You would actually find if you was to measure the contact patch yourself that it is in fact bigger than this. The width of your tread pattern will give an estimate of your contact patch width. By taking two sheets of paper and sliding them under the front and back of your tyres until they go no further you can find out the length.
At the front and back edge of the contact patch, the pressure exerted on the ground is not that high hence why we suggest that the calculation would be larger. There is barely any weight supported where the tyre is ever so slightly touching the ground. More and more weight is distributed as you move towards the contact patch’s centre.
If your tyre pressure dropped to a quarter of what it was you would discover that your contact patch does not get four time larger. Instead the tyres sidewall structure and it’s stiffness would play its part and take some of the weight.
Sports cars have low profile tyres which have short, stiff sidewalls. These tyres have less tendency to squish like those of a pick up truck or 4×4 tyres. Some tyres are so stiff they can run with no air pressure in them at all, these are known as run flats.
For all your tyre fitting needs find the best cheap online tyres at Grippy.