There are two main rules you might have heard about, or believe yourself, for making sure you have the correct tire air-pressure settings in your vehicle’s tires.
Many say a flat 32 pounds. No pun intended, but that general rule is old school and absolutely does not apply any more, as tire technologies, materials, construction and especially allowable maximum pressures, have come a very long way since the 32-pounds rule was actually valid.
Others will say to read the car manufacturers recommended setting for your vehicle, usually listed on the inside of the “glove box” door. That “rule” only applies if you have the exact same tire, and more importantly, tire SIZE, the manufacturer put on the car when they sold it to you – and even then, I would highly recommend the “new rule”. Many people do not keep the exact same tire or tire size on their vehicle, either due to putting on custom wheels and/or wanting wider tires for the appearance or handling characteristics wider tires give you.
Here’s the rule of thumb you can go by for any tire, any tire size, any vehicle; 10% less than the maximum air pressure listed on the side of the tire. If that’s all you wanted to know, give me a “thumbs up”, stop reading now and move on to something else, or continue reading if you want to know WHY this is the rule for any tire or car.
Most tire dealers won’t tell you to put that amount of air in your tires. They still mistakenly go by the “old rule” of 32 pounds or by the car manufacturers recommended setting. Speaking from personal experience, four or five different Les Schwab tire dealers have told me to put 32 pounds in both my cars, both with their own brand of tires with a maximum tire pressure on the tire side wall of 51 pounds! I run both car’s tires at 45 pounds, 10% less than the maximum on the tire wall.
The last set of tires (again, their brand of tire) I purchased from Les Schwab was always set at the 32 pounds, and they only got about half the expected tire mileage, and they wore out to the inner cord clear up on the side wall, not on the tread – because of running too low a pressure setting! They would take no responsibility for the tires wearing out so soon and in such a weird way. They said it must be the wheel alignment that was off. However, the wheel alignment was nearly spot on!
The rule of 10% less than the maximum on the side wall comes from a friend who is a race fan and has run a wheel alignment and brake shop in my area for over thirty years. I have followed his advice for three years now, and he is right! My “new” tire’s tread, since that time, is wearing very normally – at 45lbs.
10% less than the maximum on the tire side wall – that’s the new rule to follow using any tire, any vehicle.