Just got a set of Michelin tires put on my Pontiac Grand Prix, 2001. Checking the recommended tire pressure on the label on the truck lid revealed that I need to inflate the tires to 30 PSI. This seems low to me, does anyone know why the recommended inflation is 30 instead of 35, which is where my other GM vehicles are set. The tire size is 225-60-16, my other cars have 15'' tires. Would this be the reason for the lower pressure? Thanks, Terry
Who knows, every GM car I've ever owned/drove took 30psi regardless of tire size and every GM truck/van took 35psi. Except for the Dually.
Steve
Mine have worked well at 30, as recommened. IMO, 35 would give too hard a ride.
Recommended pressure is a compromise between ride and mileage. If you like a comfortable ride and acceptable handling go with the tire pressure label. If you are carrying a heavy load, want a little better gas mileage, or a little better handling go with the maximum pressure as indicated on the tire.
Or just split the difference and go with 32/33 psi
It is done so that the ride is more comfortable. If you don't care much for a softer ride and want a longer lasting tire, up it to 35 psi. The tires will wear more even. Did the old tires wear out on the side more than in the middle ? Upping the psi to 35 will make them wear even. Only downside is that the ride is a little harsher, but really not much. Try it.
It may not affect tire wear at all. The 30 PSI level may be all that is needed to give the correct contact patch for the weight of the vehicle. More air may just cause increased wear if it creates an overinflated condition.
Want to see if the contact patch on a tire is correct and check for alignment problems easily? Take a piece of chalk and rub it across the tire treads in 4 places. Now drive across a level parking lot and look at the chalk marks on the tires. if they are worn evenly across all the tires your doing good. If they are worn off on the outsides of the tires and not as much in the middle your underinflated, if they are worn off in the center and not the outside of the tire your overinflated. Worn on either side of the tires shows tow or camber problems (unless it's a swing axle vehicle like a Ford or older VW)
Well, that's why I asked how the tires were wearing. Trial and error. Every car I have owned and was told to put 30psi in by the manufacturer would wear on the sides more then the insides. Pressures were checked at least once a month. After switching to 35 psi I have gotten even wear on several cars.
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