How come if I pump my car tires up to a given pressure and then load the car?

Question

with 6 people and luggage the pressure dont go up. If I put a ton weight on the car will the presure go up?

Answer 1

The first thing that happens when you load the car is that it settles a little lower as the tyres compress, that small change increases the area of the contact patch slightly and that supports the weight. The corresponding decrease in tyre volume is small, so the pressure doesn't rise enough to be seen on a normal gage.

Then there's the issue of side wall stiffness, not all the weight is carried by the pressure, the stiffness of the side walls also makes a difference and makes the pressure rise smaller than it would be if the tyres were just like baloons. Run flat tires are so stiff that the side walls can carry all of the weight... makes you wonder why they bother inflating them... well when they are inflated the side walls aren't under as much stress so they last longer.

Answer 2

Tire has to be inflated in Cold condition. When tire gets heated up , air inside also gets heated up hence the pressure increases. This pressure increase is harmful an safe.

Manufactures specification for tire pressure relates to Load on the tire / Wheel and max operating speed. Each tire has its max load and max speed limits.

Also when you load the car Distribution of the load on to each tire matters.
When you say you have loaded with people and luggage , the load distribution can be even.
When you put 1 ton load on the car the load can be uneven and concentrated on to particular tire/ s. This may indicate as increase in pressure on that tire.
This can be checked and verified by checking the load and pressure on the individual tire with Both the said conditions.

Answer 3

If you put a ton weight in your car the pressure will go up, but good luck getting it in there. Car tires are made to support a vehicle loaded with everything that you just mentioned - if the pressure did go up noticeably with a normally filled car then it would be time to get your tires checked because they would probably be worn down

Answer 4

check your theory and you will find a very small increase ( within the accuracy range of most gauges * 1-3 lbs ) there is a much larger change due to temperature which is why your manual specifies COLD inflation pressure - it's all figured in the given pressure - just follow your manual

Answer 5

The pressures specified in the vehicle handbook are what you should use.

There are usually two sets of figures - one for light/average loads, and the other for full loads.

These pressures take into account the added weight of passengers etc.

I hope this helps....