So I recently just got 19" staggered wheels 255-40-19 in the front and 275-40-19 in the back. Both different tires have a max 50psi labeled on the outside of the tires, but I was wondering what's an actual good amount to put in them? My stocks were 35psi based on the sticker of what I should put in them. I know I definitely will not go full 50 just need to know a good number.

Thanks in advance!

 

I know there is a formula which I have no idea what that formula is. I run 44 in the rear and 42 in the fronts with my setup listed in my sig.

 

If you don't want excessive wear, just put in about 2-4 PSI over the 'stock' PSI. Example: My 18" GT/CS tires indicate 32 PSI. I would limit it to 34 - 36 PSI. With yours being recommended at 35 PSI, I would limit it to 37 -39 PSI if you so desired. If you go over that, you will be starting to throw away money from the center tread wearing down too quick. Been there, done that by mistake on an older Ford once, and now my neighbor just went through the same experience with a '98 SHO. In both instances 40 PSI was used in lieu of 32PSI. It was too much! Plenty of tread on the outside edges but the centers were gone. If seriously into racing of some type then that is a different story entirely and treadwear isn't even a concern.
** Just a side note: Too much pressure will affect ride quality and even handling in the wet. Serious things to consider.

 

Still running stock Pirelli P Zero Neros at 32psi. When my wife and I attended Skip Barber, we did run the Mustang on the track. For that the instructors recommended 45psi front and rear. But they also advised we reduce right back to 32psi once we were done.

 

I ran 42lbs in the stock Pzeros on my '10 V6 and never noticed any uneven wear at 24 k miles or something close to that when I swapped it for the '12 GT. Did the same on GT until I traded it off this summer at 22k miles. No unusual wear.

 

I will ask another TMS member to visit this thread he knows tire pressures. My tire wear is fine. I check them every so often with a tread depth gauge. The width of the wheel has to be considered also. How wide are your wheels/rims OP.

By the way great username

 

35 is great guys. I run 35/32.
40 won't hurt but doesn't ride as good. I wouldn't run any more than 40 ever.

 

32.25 here



For Al

 

For the street run what is on the door sticker. On the track, you want to see 47-48 psi hot.

 

I'm just wondering why so much on race applications. Seems like the contact patch would be much less with the higher pressure.

 

Because you changed sizes, throw away what the door placard says, and dont go over what the sidewall says.
I dont have my tire books anymore to figure out the math, do not work for Goodyear anymore.
But in short your new tire size does not carry the same weight as the OE tire at 35psi
These numbers are not accurate, but just to paint a picture
235-55-17 @ 35 psi has a load of 1500 lbs
275-40-19 @ 35 psi has a load of 1400 lbs
Each pound of pressure added the tire gains 22lbs of load

So the new tire requires more psi to handle the load.
The numbers Glenn runs sounds about right. I may have been the one to tell him what pressures to run 5 years ago, lol.

Even if you ran OE tires at the recommended 35lbs you still would see center wear on the rears, and outer wear on the fronts. Assuming you never rotated or rotated enough. Drive tires will always wear down the center. more noticeable the more aggressive driving you do.