GJarrett
Well-Known Member
Just for info's sake, there is actually a way to test out what the exact proper tire pressure should be for any tire on any vehicle... but it only works when the tire is new and if you are not running extreme camber for track application.
Overinflation will give you better fuel mileage but at the expense of rougher ride, loss of traction/grip available from the outside edges of the tread, and wearing the inside tread out too soon. Underinflation gets inferior mpg, makes the tire susceptible to wheel slippage and rim damage, and run too hot leading to premature degradation (remember the Explorer/Firestone debacle when Ford suggested run the tires at 26 lbs [to get a softer ride]?) In between those two extremes, good tire pressure plants the entire tread on the road, utilizes all the grip the tire has, wears it more evenly through the life of the tire, and garners the best compromise between comfort/wear/mpg.
You can figure out what that sweet middle ground is by doing a "chalk test". Take your vehicle out to a large empty parking lot for some testing room. Overinflate your tires (try 40lbs+ or so) and mark a line across your treads with some tire chalk. Drive the car 50 yards or so then look at the chalk marks. They should be worn off in the middle of the treads but still showing on the outside edges, because you overinflated the tires so much that they ballooned to where the outside of the tires were not planted on the ground. Remove a couple psi and do again, then keep repeating until all the tread is wearing evenly and removing all of the chalk mark, then subtract another psi or two to give the outside edges of the tread complete footing. Whatever psi you have at this point is the one that gives you the best compromise psi setting for overall use. It is also commonly a little different front and rear.
Two caveats to repeat from the first paragraph. It only works on new tires. If you've already worn the tread on a set of old tires and they haven't worn evenly, then all this chalk test will do is conform to the prior uneven wear. Also (obviously) if you've got extreme camber settings for track use, that's gonna show on the chalk lines.
Overinflation will give you better fuel mileage but at the expense of rougher ride, loss of traction/grip available from the outside edges of the tread, and wearing the inside tread out too soon. Underinflation gets inferior mpg, makes the tire susceptible to wheel slippage and rim damage, and run too hot leading to premature degradation (remember the Explorer/Firestone debacle when Ford suggested run the tires at 26 lbs [to get a softer ride]?) In between those two extremes, good tire pressure plants the entire tread on the road, utilizes all the grip the tire has, wears it more evenly through the life of the tire, and garners the best compromise between comfort/wear/mpg.
You can figure out what that sweet middle ground is by doing a "chalk test". Take your vehicle out to a large empty parking lot for some testing room. Overinflate your tires (try 40lbs+ or so) and mark a line across your treads with some tire chalk. Drive the car 50 yards or so then look at the chalk marks. They should be worn off in the middle of the treads but still showing on the outside edges, because you overinflated the tires so much that they ballooned to where the outside of the tires were not planted on the ground. Remove a couple psi and do again, then keep repeating until all the tread is wearing evenly and removing all of the chalk mark, then subtract another psi or two to give the outside edges of the tread complete footing. Whatever psi you have at this point is the one that gives you the best compromise psi setting for overall use. It is also commonly a little different front and rear.
Two caveats to repeat from the first paragraph. It only works on new tires. If you've already worn the tread on a set of old tires and they haven't worn evenly, then all this chalk test will do is conform to the prior uneven wear. Also (obviously) if you've got extreme camber settings for track use, that's gonna show on the chalk lines.
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