New Wheels, New Tire Pressure?

[SwedeSpeed95]

I just swapped my 15" stock wheels with big sexy extremely wide 17" wheels, and I was wondering what my tire pressure should be for my little 900?

They are 225/45/17 inch tires and when I got them there was like 38psi in the tires, which i think caused the god awful road noise on my test drive, can i drop it down to like 33psi?

[Rogozhin]

Drop them down, but it's because of the wear pattern on the two bad ones.

:(

I hope it helps.

Rogo

[neomagus00]

it's personal preference... i run 38 front and rear, because i find that to be the best balance between responsiveness and traction. some prefer lower pressures for a different wear pattern and less noise, some prefer higher for possibly more fuel mileage and sharper response. test and tune.

[bkrell]

I'm running 45 or so in my 16 inch 9-5 wheels.:cheesy:

[Jaws]

Wow, maybe I need to try some more pressure! I run 32 PSI on all four (15" stock rim, Goodyear Eagle RSA) and really have been pleased with performance overall to date.

[tucksayre]

I'm running 30-32 psi. I would try something like 38 before going 45 psi. I'm amazed at 45 psi you haven't had a blowout or some sort of nasty suspension problems. I'm afraid of even getting bigger rims let alone increasing the pressure in the tires because of the crazy amounts of bumps I drive over. Right now in the complex i'm staying in for the summer, there are 7 speed bumps... The sub frame brace has recently started to creak on hard turns at slow speeds, probably a bolt or something has loosened up.

[bkrell]

Well, I was always scared of high tire pressure, too. When I got my last new set of tires, though, the shop that installed them said they barely ever put below 45 psi in a tire and usually have to put 50 in the really low profile, large diameter tires. I just kinda thought they were nuts.

But when I started reading all the hypermiler websites it is apparently something they all do for max fuel economy. These guys all inflate their tires up to max rated pressure and claim to never have a problem. I did a little digging around on the internet and found several sites where they were stating that most manufacturer specs are only for a good balance of comfort and handling.

One site gave the example of the Ford Explorer/Firestone debacle, saying that higher pressure was never an issue as much as too low a pressure. For the spec'd tires, the pressure Ford used was the minimum recommended pressure that Firestone wanted that would not cause issues with heat and friction. Firestone had wanted them to spec more pressure, though, so that the tires would have a reserve of a few PSI to account for folks who don't check pressure regularly. But evidetally Ford was more worried about the higher PSI causing the ride to be to harsh and went with the absolute minimum safe pressure... We all know the rest of the story.

I can believe it because my Honda CR-V specs the tires be inflated to 26 or 28 PSI. After a year or so, I balked at that and went up to at least 35 and never had an issue with the tires, just a tad more NVH. My tires spec 51 psi as the max inflation pressure so I think I'm probably fine with 45 psi.

[tucksayre]

I might move mine up then to something like 38-40. If the ride works out fine, I might go even further. Thanks for the input. I might just turn the music up to compensate for the random rattling interior pieces:D.

[Jaws]

Overall traction will suffer at higher pressures, especially in the wet. These days we need all the mileage we can get though.

[mrzuzzo]

:p mine were around 50 (yokohama/gislaved winters) for the past few months and no issues except for horrible traction at the expense of really good mileage. I got an oil change last night and the they dropped all 4 back down to 32psi, the ride is a bit more comfortable now..

[Jeremy R.]

The factory tire pressure for 215/45R17 tires is 32 PSI front and 29 PSI rear for speeds up to 120 MPH, or 38 and 35 if you're doing over 120. I'd assume the 225s are about the same. I keep mine at 32 front and back. Right now I have 215/45R17 tires on the front and 225/45R17 tires on the back.

[SwedeSpeed95]

The problem with super high pressure is that the middle of the tires wear a lot faster than the sides

[bkrell]

Yes, and I am going to watch for that. Should be easy to tell...

[neomagus00]

The problem with super high pressure is that the middle of the tires wear a lot faster than the sides
unless you're like me... i have lots of negative camber somehow, which wears the insides when i'm <50 mph, and i corner really hard, which wears the outsides quite well. it all balances out in the end :cheesy:

[Adam@Z1Auto.com]

larger wheels do not mean more or less pressure...use the same pressure as recommended in the owners manual to start, and adjust up or down as comfort/performance/tire wear dictate

[Loobis71]

I usually run 35psi or so in the 17s (summer only) on my 900.

The winter 16s I keep at about 32ish.