robnalex

I recently posted a questions about tire pressure for the Michelin Pilot Sport A/S 225/50/17 for our car.

It seems that most of you who have these tires are keeping the psi higher than for the stock tires because they are slightly larger tires. Most seem to be running this tire mid-30's (34-37 psi).

At 34-35 psi I found I could make the tires spin on a wet road.

I checked with Michelin, and they said that even though it is a larger tire, because this tire has a greater load capacity than the stock tires, the cold pressure should be lower (30 psi) in order to have the correct amount of tread on the road.

In other words, because these tires can take more vehicle weight, the psi needs to be lower than for the stocks. For more information you can call Michelin at 800-847-3435.

Scrib

Thanks for the info...

While it sounds 'logical', what does everyone think about their comments are tread life? It would seem that lowering the PSI from what most of us have, 35-37psi, that we'd really take a hit on the tread life AND the gas mileage...

Thoughts???

Zapata

well, lowering the PSI would increase the contact patch but it on an AUTO CLS it doesn't help traction one bit. HOwever, mileage will suffer!

robnalex

The way I understand it. These tires can handle more weight than the stocks, so we need to lower psi in order to compensate. Otherwise we don't have enough tread on the road. So if you kept your stocks at 32-34 psi, the 225/50 should be at 30-32 psi.

Another way of looking at it is that our car is actually "lighter" on these tires because they have a higher load capacity.

The folks at Michelin were very good at explaining this. You can call them at 800-847-3435.

CO-CL-S

good info, I had never thought or it that way (lower preasure to get then nominal patch onto the road). thanks..

robnalex

What do you prefer? Better mileage and poorer performance? Understand that the "equivalent" psi is lower, but the "effective" psi is the same. The idea is to have the same amount of tread on the road that you would have with the stock size- not more, not less, but the same. If you use the same or higher psi that you used for the stocks, which have a lower vehicle weight capacity, you will end up with less tread on the road and a higher "equivalent" psi pressure. In other words, if you used to run your stock 215/50 at 33 psi and you inflate your 225/50 pilot a/s to 35, you are actually running your pilots at the equivalent of 37 psi.

Smitty

Lower it and listen to those babies squeel like little piggies when you take a nice hard turn.... You should always run the recommended PSI that is stamped on the side of the tire.. regardless... Wait till you clown the car up and get 4 people in the buggie...

But way to do your homework... i would use less tire pressure at the track only!

Smitty

CO-CL-S

I don't think recommended PSI is stamped on the tires, only the MAX PSI is stamped on the tires, because they don't know the weight of the car?

robnalex

The psi on the tire is only the maximum safe inflation pressure. Correct psi is based on the vehicle weight and maximum load capacity of the tire. The tire (or tire manufacturer) doesn't know how much your car weighs, so there is never a recommended psi stamped on the tire.