Why Do the same size tires say they can hold different amounts of air (psi), and does that matter?

Asked by: Pam Abrahams

Because all vehicles are different, weigh different amounts and carry their weight loads differently, vehicle manufacturers make sure to specify the tire psi that will operate best for the given car or truck. Both values are safe to use with your vehicle.Nov 26, 2018

Why do the same size tires have different psi?

Typically, if the engine is located at the front of the vehicle, the front tires will have a higher PSI to support the extra weight. If a vehicle has an engine in the back, the back tires might require some extra tire pressure. Their ideal PSI might be higher than the front tires.
May 3, 2022

Why do bigger tires require less psi?

If you have two different sized balloons holding the same amount of air, the smaller balloon would have higher pressure than the larger balloon. Therefore, a larger tire needs less pressure than a smaller tire to carry the same vehicle weight.
Nov 19, 2015

Does tire pressure depend on tire size?

The psi (pound per square inch) is based on your vehicle’s total weight and size, towing weight capability, and recommended tire size.

Does tire pressure need to be exact?

Perhaps the most important point in all of this is to find and use the correct tire pressure for your vehicle and that is not the number on the side of the tire! Most vehicles have an optimum tire pressure of 33-36 psi, but the specific pressure for your vehicle can be found in the car’s owner’s manual.
May 2, 2018

Why do tire shops over inflate tires?

So why do dealerships and shops over-inflate your tires then? Dealerships don’t intentionally over-inflate your tires, in fact they likely inflate them exactly where they should be. However due to the differences in heat, the air in the tires will expand once the tires move from the cool shop to the warm road.

Can 2 psi make a difference?

So, when filling your tires, the recommended tire pressure is the best compromise between handling, comfort, fuel economy and safety. But it’s certainly fine to go over the recommended inflation by a psi or two.
Apr 5, 2020

Should your front tires have more pressure?

Tyre pressures are normally higher in the front than the rear, to compensate for the extra weight of the engine and transmission, especially on front-wheel-drive cars.
May 5, 2011

What happens if your car tire pressure is too high?

Tire Damage and Wear



Excessive air pressure can also distort the shape of the tire, leading to decreased traction and increased wear and tear down the center of the tire. Depending on the circumstances, repeatedly overinflated tires could wear out more quickly.
Feb 22, 2019

What happens if you inflate your tires too much?

Overinflated Tires Wear Out Your Tires Faster & Unevenly



Uneven tire wear can also be the result of overinflation. When your tires have too much air it causes the center of the tread to bow out and wear first. Because of this you will need new tires more often and have a less than comfortable ride.
Jun 27, 2019

Is 40 PSI good tire pressure?

Specifically, the level of 40 psi can be suitable for passenger cars or sports cars. But this is too high for small cars with a recommendation below 35 psi, while 40 psi is too low for large trucks. The recommended level for the tires of famous sports cars and passenger cars is between 32 -40 psi.
Aug 10, 2022

Is 36 PSI too high?

“Recommended cold tire pressure is in vehicle manual and on tire label. It’s usually 30 psi for small, 36 psi for medium, and 42 psi for large car.”

Do aftermarket tires require different PSI?

If you have aftermarket tires of same sises and Loadrange , though the brand or model is different , then in general you can use the same advice pressures.
Oct 13, 2015

What is the 4 PSI rule?

The 4psi Rule



Park and measure the pressures in each tyre – do all four tyres as the weight distribution from front to rear will see different temps and pressures. If your tyre pressures have increased by 4psi then you’re spot on with your starting tyre pressures and there’s nothing else to do – easy.
Sep 23, 2020

Should you overinflate tires in winter?

Just because the temperature is dropping doesn’t mean it’s a good idea to overinflate your tires. Your vehicle was engineered to perform best with the tires inflated to the manufacturers recommended pressure. Stick to those numbers, and your tires will perform at their best.
Dec 11, 2018

Should I slightly over inflate my tires?

Exceeding the optimum tire pressure is not recommended for many reasons. Tires will wear out prematurely. Overinflated tires round out on the tread section and cause the center to wear down significantly faster than the outer edges. This could cause them to last only half as long as they typically would.

Why are my tire pressures different?

It’s the same as when you drive at higher speeds for an extended period: the tire warms, and the air within expands and increases pressure. In the morning, the air temperature is just rising from overnight lows, and your tires are still cool from being parked. The air pressure in the tire is at its lowest for the day.
Sep 27, 2018

Do different tires have different PSI?

Because all vehicles are different, weigh different amounts and carry their weight loads differently, vehicle manufacturers make sure to specify the tire psi that will operate best for the given car or truck.
Nov 26, 2018

Does rim size affect tire pressure?

Since the tire gets wider with a wider rim, we increase the dimeter in our pressure equation above. This results in a lower tire pressure for a wider rim with the same size tire.

Does rim size affect TYRE pressure?

Wider rims are make tires more stable and the air volume is increased, so you can lower your pressure. Running a larger diameter 29″ rim compared to a 27.5″ with an identical rim will also increase the tire volume.

What is the 105 rule?

The Rule of 105 states that the rim must be at least 105% the width of the tire if you have any chance of re-capturing airflow from the tire and controlling it or smoothing it. One of the most interesting aspects of the Rule of 105 is that before 2001, nobody was tunnel testing with 21 or 23mm tires.
Nov 29, 2021

How much air should I run in my 35 inch tires?

Well-Known Member. For a 35″ you should be in the 28-32 range on road.
Aug 23, 2018