Re: Tire Pressure

Posted by Owen_Dyneto On 2013/3/22 14:04:07

It's not uncommon to find cars today with tires of different sizes or construction or capacity ratings than were originaly specified. For example 6-ply "rated" tires substituted for original full 6-ply, and so on. And finances might cause some of us to undersize a new tire purchase a bit. So.... the original inflation specs may or may not be the best guideline.

When I first put new tires on a car, I estimate the road weight of the car with a typical passenger load, gas, oil, water, tools, etc. Then I mulitply the maximum load rating (at it's maximum inflation pressure) of the tire by 4 and compare to the gross vehicle weight. If I've got lots of freeboard then I know I can go to lower pressures for a gentler ride if I wish. But if I find I'm right at or neat the cusp of the vehicle weight, I keep the pressure at or near the maximum inflation pressure. This is a lesson some learned bitterly in the Ford Exlorer/Firestone tire fiasco of some years back! My cold inflation pressures for both cars is about 4psi below the max.