Art161

I don't think it's as simple as that. You have to consider vehicle dynamics when traveling at high speed, when turning, etc. And you also have to consider the suspension setup. That's why camber, caster, and toe are different on different cars.

mustangspotential

This is interesting to me because my wheel/tire combo came from AM with Nitrogen. When read with psi gauge, it reads close to 40. I'm not familiar with nitrogen fill, is this normal?

PNYXPRESS

NEVER inflate a tire to the max pressure printed on the tire. The easiest way to figure out the air pressure to run would be to ask a 2010+ owner with 19" stockers what Ford recomended for their car.

Goldenpony

I run 1-2 PSI over the recommended pressure on the door frame sticker.

l00kitzzlilcj

My wheels came from AM too, but i opted for regular air because i dont have nitrogen laying around in my garage that i can fill up whenever lol.

I think I have put like 700 miles on the tires so far. Winter got brutal up here between snow and pot holes so my stang didn't leave the driveway for about 7 weeks. I dont really see much treadwear yet but it looks like the outside is taking more than the inside. My camber changed a tiny bit after i put the wheels on.

Art161

They might have shipped them with 40 psi so that you could bleed off the nitrogen to the pressure you want. Not many people have a ready supply of nitrogen handy. If the tires were shipped with a lower pressure than you wanted, it could be a hassle for you.

BTW, I'm a believer in nitrogen. I use regular air because of the inconvenience of getting nitrogen. The guy who parks next to me had his tires filled with nitrogen, and they rarely need more added. My tire pressure goes down about 1 psi per month. The nitrogen molecules are larger, so less leaks out. Also, nitrogen is dry, so you won't have moisture rotting the inside of your tires, although I've never had that problem with regular air.

Chromeshadow

I got my summer tires -Nitto 555s 255/45/18s from AM, they recommended 35 lbs. After about 30,000 miles the tread wear is perfectly even. This means to me that the whole tread is contacting the pavement evenly. If the inside tread is not wearing the same as the outsides, (low air pressure) I believe your not getting as good of grip as you can if the tread wear is even. The PSI can vary with the weight of the car and the width and height of the tires. I glad AM gave me the correct answer. My door sill says 32 lbs-that is for the factory 17" wheels and tires, it does not know what tires I have on the car.

l00kitzzlilcj

How did you get the recommended pressure from them?

Chromeshadow

Their e-mail address is support@americanmuscle.com

Hey Russell,

Thank you for emailing. We usually inflate the tires to 44 psi for shipping
purposes, but recommended pressure is usually between 35-38 psi. Keep in
mind you must have the pressure within specification of the TPM
sensors(32min-38max) in order for them to sync up. Once you have
successfully synced them to the vehicles computer, you can adjust the
pressure accordingly. Please let me know if there is anything else I can do,
I will be happy to help. Thank you.

Ken Cruz
CS Supervisor
AmericanMuscle.com
(866)-727-1266 x 325

Norm Peterson

There are standard load vs inflation tables to help figure this out, but they aren't generally publicized.

I'm assuming that you started with the 235/50-18's, which are a standard load (SL), Load Index 97 tire. The 235/55-17's are load index 98, which isn't enough different from 97 to matter here.

Your 245/45-19 front tire choice will maintain the same load capacity at 32 psi whether it is a SL 97 load index tire or a 101 load index XL (eXtra Load) tire (it's complicated).

Your 275/40-19 rear tire choice is either a 101 load index in SL or 105 in XL. This is a slightly larger tire in terms of load capacity and could be run at 29 psi and still match the load capacity of your OE tires.

Summary:
OE . . . 32 psi front, 32 psi rear
New . . 32 psi front, 29 psi rear

But . . . feel free to experiment from there. You might like the handling better at 35 psi front and 32 rear. For street duty, I wouldn't go any higher than about 37 & 33, though.


Norm