Before I bite the bullet and purchase these 225/40/17, any advice. Anyone tried them. I remember a post in which someone had fitted 235/35/18. It seems to me to be the logical progresion of 205/50/15 - 215/45/16 - 225/40/17. They are to go on the latest 17 inch prodrives, std my99. Thanks.

 

I would recommend the 215/40 x 17 size for several reasons.

1) It keeps the correct rolling radius to keep the speedo correct based on a standard 205/50 x 16 size (205/55 x15 if you have 15 inch wheels).

2) Tyres that wide may rub at the rear, particularly against the rear struts. Put you hand behind your wheel, and you will find there isn't a lot of room. I have 215/40 x 17 tyres, an there is less than a fingers width between tyre and strut.

3) The wider the tyre, the more likely you are to suffer tramlining, and aquaplaning in the wet.

4) The Impreza can generate more than enough grip using the standard 205 tyre width. Unless you have modified suspension, you won't really get any advantage grip wise from the wider tyre.

5) Cost. A 225/40 will be more expensive than a 215/40 (a very popular size with lots of choice and range in prices).

6) Prodrive recommend 205/45 x 17 P Zero tyres. Why ignore a good recommendation ?

7) I think the cars fitted with 18 inch rims have required suspension and/or rear wheel arch mods to get sufficient clearance, particulalry under heavy suspension loading.

Thats probably enough reasons

 

Thanks, 215 it is

 

Prodrive might "recommend" P Zeros, however the WRC team and Catalunia trip members really struggled on P Zeros!