the alignment shop put my front tires at 37.5lbs and the rears at 32lbs. is there any reasoning behind this or should i even them all out?

 

Actually, there is reasoning behind that but, I don't know if I could completely cover it right now. Basically, I suspect you told them about your suspension...before they did the work and they figured that up front was a little softer than they like so, they added a couple lbs.

 

I think they should all be at 32.

 

Look at the tire sidewall and go by that. Different tires have different MAX PSI ratings. The pressure you go with will affect so many things on the car.. mileage, handling, comfort, safety, etc. Most of which comes down to personal liking. Harder tires (more psi) will give better mileage on highway trips however you feel every pebble you hit. 4x4ers running sand hills for example will use 10psi.

A safe bet is to set them all to 32psi take it for a drive and then increase/decrease the pressure in small 2PSI increments until you like the feel. It really can change the feel of the car a lot.

 

Don't actually use the sidewall pressure as an operating pressure. That is the maximum pressure that you should put in the tires, not the recommended pressure. And unless you have a 460 in your car, you shouldn't be at the max pressure. You can use it to know what not to exceed, but that's it.

There are many things that affect ideal tire pressure. Weight of the car is a big consideration, and lower profile tires (like yours) will take a bit more pressure than taller tires will, simply because they need more support in the middle to keep them wearing even. Also, different driving habits will change ideal tire pressure. My roommate ran 40psi in his 275/45ZR17 Goodyear F1 GS-D3's on his '97 T/A. It got him slightly better gas mileage and put more wear on the center of the tread to account for all of the shoulder scrub he was getting from turning aggressively.

The idea is to get even tire wear at the end of the day. If you do a lot of highway driving, a lower pressure may be better to keep from burning the center of the tread out. If you do a lot of high-G cornering, you may want a higher pressure. Of course, setting the tire pressure for optimal performance (ie. autocross or drag racing) is a different thing altogether, but I'll assume you're not doing that.

With your very light car and low profile tires, I'd start at 32psi and see how the tires wear. Use a coin in the tread to gauge (or ideally a depth gauge) tread wear at the middle and outside edges of each tire. If you're getting more wear on the outsides, increase pressure. If you're getting more on the center, reduce pressure. Remember to set tire pressure when the tires are cold. Also, get yourself a decent gauge, preferably a dial gauge. Don't rely on gas station gauges, which are notoriously inaccurate.