16's to 17's What tyre size?
 

I have an all standard MY97 WRX STI version 3 and want to change the 16 inch wheels for 17's. How do I make sure the tyre size is correct. I have heard people talk about 205/215/225 40/45 etc. Which is the correct profile to keep the speedo true or is there always going to be some inaccuracy because of the change? And which width should they be run on to avoid unnecessary tram-lining?

I have the same car as you.
I have a set of P1 17's with 205 x 40 tyres which are SMALLER in diameter than the 16 x 205 x 50 stock tyres.
If you have 205 x 45 x 17 you should be spot-on
225 x 40 x 17 may not be made, but you might have rubbing on the inner lip of the wheel arches.

Any good tyre centre will advise you, but the best place to check is the tyre manufacturer's web site.

Hope this helps,
Graham.

I have an STI 2 and have gone to 215-40-17 tyres. Very happy with grip, and wear...

Thanks for those ideas, but I thought, maybe, if you increase wheel size by 1 inch, you would drop profile from 50 to 45, whether it's 215 or 205. Yes or no?

Original 17's came with the 205/45/17's but the choice of tyre is limited in this size.
Most people go for 215/40/17's and occasionally 215/45's from newage wheels:thumb: