Hi All, I was wondering what the general consensus was on needing alignment after moving to a different set of tires and wheels. I went from OEM CS 18" wheels to the following:

Rim
Front 19x8.5
Rear 19x10.5

Tires - Potenza
Front 235/35-19
Rear 275/35-19

Do I need an alignment? Also as a side, does tire pressure need to be changed from original specs?

Thanks for any input!
-Moto

First, I don't think you would need an alignment just by changing the wheels and tires, but see how it drives to determine if you need to have it realigned.

The tire pressure will definitely change. Per the owners manual for 19" wheels, the fronts should be 32 psi and the rears should be 36 psi. Make sure you change your TPMS setting to reflect the 19" wheels.

Lastly, check to make sure you are not rubbing up against the parking brake line with your rear tires. Since your rear tires are much wider than stock you might want to check your clearance on the inside. Look at this thread of K-Man S': Strange sound only when moving forward?

You may need to reposition your parking brake line so this doesn't happen.

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Thanks TX-KmanS!

Yeah, I saw that brake line issue with K-Man S and it got me a little worried. I have to go in and check it out to make sure but I think I'm good as I have smaller tires. As for the TPMS, I don't have to worry about that either as I do not have that option.

Thanks for all the heads up!
-Moto

To determine your optimal tire pressures, get a pyrometer and start with the above pressures. Once the tires are warm, check each tire tread inner third, middle third and outer third. If the middles are consistantly higher than the inner/outer temps, you're over inflated. If the inner/outer thirds are higher, you're under inflated.

If your inner temps are singificantly different than your outers, it means you'll likely benefit from a camber change, i.e. if your outer temps run higher than mid and inners, you need more negative camber.

Good luck.

Greg

This is a case where you want to check the actual tire pressure plate on the doorjamb. Mine says 32/37 w/19"s

275s are wider than OEM though so I have no idea if that changes something too.

Yes, the manual is a misprint - the pressure for OEM 19" is 32/37, although I've checked this out with a pyrometer and found it to be slightly under-inflated. I've been running my PS2s at 35/40 and have found it to be a better street pressure - much more responsive and the pyrometer shows even temps all across.

It will also depend on which Bridgestones you're running... but, I would say that a good place to start would be the 19" pressures on the door plaque.

brad

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Thanks everyone! Now, the question I have is, where can you buy a pyrometer?

-Moto

start here: Results 1 - 10 of about 771,000 for pyrometer

pyrometer - Google Search

brad

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Are you tracking or AX'ing your Croc? If not, I would say don't worry about it; use Brad's pressures and be happy. And if you are doing anything on the street where you would notice a difference in tire pressures (short of gross over or under inflation), please tell me where you live so I can make sure I am somewhere else

Seriously, tire temps are meaningless unless you take the car to a skid pad. You would likely need to be grossly over or under inflated to see a big difference in the temps based on a run down the freeway. To really know what is going on, you need to do several minutes on a skid pad, and let the tires get good and hot, then measure them immediately. At that point, the data you get will be meaningful.

And if you do that, I would bet dollars to donuts that the outside edge is way hotter than the center and inside edge. Unless of course you have a ton of negative camber; not likely w/o major mods.

Further to all that, in my experience unless you are grossly over or under-inflated, pressure adjustment is really a matter of the spring rate of the tire. Fore and aft adjustment of the pressure balance will have a profound effect on the balance of the car.

Its amazing how a slight understeer or oversteer tendency can be dialed out be adding a few pounds to the opposite end of the car that is having the problem. Of course, that also assumes that the driver is not overdriving the car. Any car with any set-up can be made to over or understeer at the hands of the driver.

But again, thats all really only relevant to track/AX situations.

Brian

Thanks Beez,

I was hoping for a store that I could just drop by and pick one up. Like Home Depot but no such luck.

-Moto

Very good points BGLeduc. My intention is not to track the Croc but you never know. I was looking at ways to "maximize" the life of the tire (considering how expensive tires can be) and balancing that with optimal handling on the occasional back road twisty.

-Moto