need a good tire pressure for 225/40/18 tires?
 

im running 39 in the front and 38 in the rear, is that good? or should a go a bit higher

I would say thats a bit too high. Im running 32 in the front and 30 in the rear.

Over inflating your tires is dangerous and will wear them out faster. Not to mention your ride is going to be rougher.

depends i run higher due to all the pot holes in hawaii.

Do you run tire pressure close to the max psi, or how do you know what to put in? I've always ran my tires about 5 below max psi... but I never knew what the rule was since only max is listed on the tire.

I keep my tires around 35psi all around. I think when they gave me my car back (the shop) they had it up around 38psi. I prefer to have it a bit higher because the ride feels better to me actually.

"Over inflating your tires is dangerous and will wear them out faster. Not to mention your ride is going to be rougher".

Just replaced my Toyo Proxes 4 at 39,900+miles...with tires inflated at 38 lbs since getting them back in '05...I don't think it wore out faster...I could have gone another 2k+ miles with them...

I normally use the following equation for tire pressure.

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

(2700/100 = 27
+2psi = 29psi
=2 in the front for 31psi

So according to that formula, 31psi up front and 29rear is acceptable.


Too much tire pressure may have less rolling resistance, but it is more prone to punctures. The ride quality may also be more stiff. The wear of the tire may be concentrated to the center. The contact patch will primarily be in the center, so say goodbye to cornering grip.