currently i have the stock tires on my 2.5i (205/55 16) and i was wondering if i put 17 rims on and went to a 225/45 17 setup would those tires require more psi then the stock ones....cause right now the plate say 33psi front/30psi rear for the stocks...also what would be needed so the speedometer is not messed up by going to a larger setup, or is there a +/- range the speedometer can be at?

as you can see i don't know much about tire setups and the like, trying to learn...i'm not even sure 225/45 17 is what i want but i know it seems to be a common set i see people using

 

That size should work, I know it's good for a WRX. Inflation recommendations for a 215 (close enough) should be on the inside of the door jam. I think it's like F33/R32 or something like that.

Speedo changes can be calculated here http://www.miata.net/garage/tirecalc.html .

Here's an explanation of what all of the numbers represent.

On a 225/45/17 tire the 225 is the width in mm, the 45 (profile) means 45% of the width which in this case is 45% of 225mm and the 17 is the wheel od in inches.

This is the way to figure out the od of a tire. (I will use a 225/45/17 as an example)

(1) multiply the width and the profile (225x.45=101.25mm)
(2) multiply x 2 (101.25x2=202.5mm)
(3) add the od of the rim (1"=25.4mm so 17x25.4=431.8) (202.5+431.8=634.3)

BTW, your stock tires have an od of 631.9mm so as you can see you're only increasing the OD of the tire by 2.4mm.

 

so upgrading to a 17" from a 16" and then going with 225/45 17 is a good idea? or should i just stick with the stock rims and just get better rubber?

or maybe just go with the stock 17" from the WRX which is what 215/45 17

 

Unless there's a difference in the 07 2.5I that I don't know about I'd think a 225 will work just fine as long as the offset of the new wheel is good and your rim is at least 7.5" wide.

The choice between 16 and 17 is completely up to you. I like the performance and look of a 17 better and that is why I went with a 17.

Have you or do you plan on lowering your car and do you plan on doing any autoX or track days (what's your plan for the car?)?

Whats your budget?

 

i do plan on lowering it eventually, as for autox i highly doubt i would wanna do that any time soon, maybe some track days...right now im just spending my time reading up on mods that work and trying to make up my mind on what i want to ultimately do (i suck at making decisions...)

 

I'm with you on that one and that is why it's a good idea to take your time, research, ask questions and try to get a future plan figured out.

I'm running Rotas (17X7.5/48mm offset) with 225/45/17 S03's, the car isn't lowered a lot with Ground Controls (rear), I'm running -2 degrees of camber and I rub the rear fenders when I'm pushing the car hard but I'm willing to deal with it for the added contact patch. If I had to do it again I would have looked for a 50mm offset rather than 48.

I don't know if I drive my car harder than others on the boards but a lot of people are running 225's and wider with no problems.

 

yea im leaning towards 17's and doing the 225/45 setup, but what exactly does the offset mean? i read that it is the distance from the center of the wheel to the hub or something like that, but can you run any offset you want or do imprezas have a max/min they can accept?

 

Here's a great thread that will answer a lot of your questions. Post #8 will deal with offset. https://www.i-club.com/forums/wheel-tire-59/official-tech-thread-tire-rack-55297/

The offset will depend on the width of the wheel. I copied and pasted these numbers off another thread and they can be used as a general rule of thumb.

Width .... Offset

6.5" ....... +53 to +55
7.0" ....... +50 to +53
7.5" ....... +47 to +50
8.0" ....... +43 to +47