I received a Private Message last night on one of the many forums I frequent and it is a common one. I’ve cropped down the users original question and cleaned up the answer a little.

Quote:

Originally Posted by p********g whats up man, im due for new tires and im kind of torn whether or not to go big for the “hey look at all my rubber” look or just to stick with what works. im running advan rcII’s 18×8.5 +45mm currently with 235/40 18’s. i have been thinking recently of upgrading to some 265/35 18’s and rolling the front and rear fender, but would first like to hear the pros and cons of each tire if possible. i dont do any track driving or autocross, but do hit up some canyon days here and there, but would mainly like the bigger tire for simply “the look” get back to me whenever you can at your earliest convenience, and be as candid as possible, thanks in advance -e

 

E,

I’m familiar with your setup, the RCIIs look very good on your car.

As you see with the 235/40/18 tire you’ve got a decent amount of room at +45mm offset all around.

Fronts don’t really require a fender roll but if you’re doing it you might as well, to help clearance in the front you can add a little more negative camber (~-1.8 or so would be good).

With a fender roll in the rear you should be able to safely run a 265/35/18 with your 45mm offset wheels.

key word is should, you may have to “pull” or “flare” the rear slightly due to you being on springs and not stiff coilovers. Also, you may need to invest in some rear camber bolts (Ingalls work well) to dial in a little more rear camber to keep the tire away from the fender.

Being an 04 you can’t get around not rolling your fenders, unfortunately you don’t really have a choice there if you want to run wider than a 235 (at your current width/offset/suspension).

which tire were you thinking of running?

a 265/35 is a fairly common size and most Max Performance Summer tires come in that size.

another size to look into is the 255/35/18 (RE01R specifically). This will be better suited to your 8.5″ wheel and will have less rubbing issues in the rear.

now that you know it is possible to make it work, I’ll tell you the downsides of running wider tires.

the bad:

1.) Your car will find every groove in the road and start trying to follow it like a blind dog on a leash. Now it isn’t that bad really, as long as you’re paying attention. (i’m running 265s and -2.9 camber in the front, trust me I know what it’s like ).

2.) you will give up some steering response for the increase in total grip. it’s a trade off that is a hard one to decide if it is worth it or not. the decrease in steering response wont be that much going from 235 to 265 on an 8.5″ wheel, and the ultimate grip wont be that much either, at least not on the street (or canyon). I hope you’re not pushing 10/10ths out on those canyons.

3.) there will be some added roll over which you may or may not notice, it really depends on you as an individual. Some people can tell when their camber is off by a 10th of a degree. I’m not one of those people btw,

the Good:

1.) they’ll look beefy as hell
2.) You will have more grip at the limit if you get there.

The above would also apply to all Base Imprezas and WRXs as well as MY04 STi’s. For a MY05+ STi the tire talk is similar the only real difference is the fender rolling. On a MY05+ STi fender rolling tends to be more complex and it can be easier to actually cut the fender lip off versus rolling it. I will address fender rolling and trimming in a future article. 

 For all Models Suspension does play a roll, I removed the specific suspension in this so it isn’t assumed it will always work.

If there are any specific questions such as this don’t hesitate to email me or shoot me a PM on one of the many forums.

 -t3h_clap