drgrant

Anyone else running these on AWD? I have Michelin PS4S. Right now I am doing 36 PSI front and 37 PSI rear (cold) but was wondering if anyone with same size tires found going higher or lower is better?

-Mike

bob256k

Thepsi is usually listed on the sidewalk of the tire; I know that you have to raise the psi based on load the tire handling but that only really comes in to play with SUVs.

drgrant

Yeah it just says 50 max, which obviously is too high for these things in actual use. I just didn't know how different they were from the stock P235/40R19s being that the tire is slightly fatter.

-Mike

bob256k

I have tires of the same profile but by Michelin, and the dealer always inflates them to 35. I would stick at that psi. I have tried higher PSIs but it just gives a rough ride. Plus as you drive the tire will heat up and the pressure will rise. Typically after a long drive the tires are at about 40-42 if it is a warm day. In cold weather your might have to air them up as the cold will cause the pressure to drop inside the tires.

azipod

The psi on the sidewall represents the maximum psi designed for the tire. Never inflate to that number!! It’s too high and will get higher in warm weather and after some driving. Inflating your tires to the number on the sidewall is asking for serious trouble!

The proper psi for YOUR particular car is listed clearly on the drivers side door jam. If you like spirited driving, you can increase it a couple psi.

bob256k

He's right never inflate to msc psi sorry, some tires have a minimum and a Max psi. Mines say inflate to 35 and Max is 50. I never inflate to 50 always 35

drgrant

Yes, I agree with all of this, but the issue is that P245/40R19 is a little "off the reservation" and I was wondering if the tires should have more or less air than the P235s....

azipod

That’s a good question. The thing to understand is that tire pressure is based off the weight of a vehicle. It doesn’t not matter the size of the tire. The correct pressure for your car is noted in a sticker in the drivers side door jam.

A larger size tire simply uses more air, because it has more volume. But that has nothing to do with the pressure. The pressure for a give car, should remain exactly the same regardless of the tire. The only exception is the donut spare, which is a totally different type of tire.

One should always stick to the tire pressure as recommended by the manufacturer on the door jam. As I had indicated before, you can increase it 2-4 psi for better fuel economy, better performance, or to simply stiffen the sidewall if you have low profile tires (to provide slight rim protection) and run on roads riddled with potholes.

Byprodrive

iTrader: (1)

I highlighted in bold what is wrong. A larger tire has more air volume so it doesn't require the same air pressure to support the same amount of weight.

azipod

I disagree. Where are you getting this info? That might be true if you are upgrading from a 18” stock tire to something like 28” or something gigantic, but obviously that doesn’t apply to real world scenarios where we are doing a +1 or +2 setup.

https://blog.tirerack.com/blog/docs-...r-my-new-tires

Byprodrive

iTrader: (1)

From the 4 different tire stores I worked for in 2 different states.

azipod

LOL. I’m not sure what they are teaching you there but I’m sure not going to ask you the name of these “shops.”

Seriously. Please stop giving out bad advice here to everyone. Implying to our community here that its OK to lower the tire pressure when we put on larger tires with new wheels is so not cool! Terrible advice!