Hey everyone,

I KNOW about the search button and have been reading NASIOC for years now ever since my 03 WRX. But about 2 weeks ago, I got my new baby (2005 metalic grey STI) and have been loving every minute. BUT.... Here in the mid-west, snow is on the way and these AWESOME summer tires are gonna have to be pealed-off and replaced.

Here's the deal: I know all about "smaller tires being better for snow" but I would also like to go up in with for year round. I would like to change to Pirrelli PZero Nero M+S but don't know what size for sure. I have the 05' BBS 17x8" wheels with a 53 offset (standard 225/45/17). Some will say that 245/40 will fit, while others say you have to roll the fenders (which I'm not going to do). AND I would rather stay at about the same overall diameter as the 225's. Would either one of these tires be okay on that stock wheel?

235/40's : not going to consider
235/45's : would be nice except, will it through off the gears or anything?
245/45 : would LOVE to have, but not going to modify fenders

So PLEASE reply if you know for sure they will fit. I have read a LOT about 04 sti's not neccesarily being able to fit or they rub. But I can't find too much info about 05 STI owners and what they have done. But I also think it's due to the differance in offset.

Thanks in advance....

DSTI

Considering Japanese '05 STis have 235/45/17, your best bet would be to go with that size.

235/45R17 will be a good choice for winter use instead of 245/40 for the simple reason of ride height. The 245/40 will have you roughly 1/4" lower overall to the ground. However, there will be significant handling differences between the 235/45 and the 245/40.

255/40/17 is closest

DSTI -

I'm at this point now, what tires did you end up getting?

- Tom

245/40

245/40 too

Cool, thanks guys.

Quick question, I heard with the stock 225/45/17's the speedo is off. So if I were going 60 mph it would read 63 mph or vice versa. Do either of the 245/40's or 235/45's make up for that?

I thought only the size of rim change the speed!?

Cool, thanks guys.

Quick question, I heard with the stock 225/45/17's the speedo is off. So if I were going 60 mph it would read 63 mph or vice versa. Do either of the 245/40's or 235/45's make up for that?
When I've clocked my car in the speed test zones on the highway, with cruise control set to 70 on the speedometer, the actual timed speed would actually be 71 and change.

That was on fresh stock RE070's. As the tire wears, it will slowly go the other way - a tire that is almost worn out might give you a speedo reading of 70mph when you're actually only going 68

I thought only the size of rim change the speed!?
rim size has basically nothing to do with speedometer reading. Only the tire's outer diameter has anything to do with speedometer reading. This spec is given by all manufacturers as the revs/mile.

245/45-17 should work on the stock wheels without rolling. Some of the A Stock autocross guys say 255 will work.

I am running 245/45-17s on 8" aftermarket wheels (+45 offset), and did need to roll the rear. Am about to roll the front too as it is rubing once in a while under hard use (track/autox), with a front ride height of -1.5".

But with the stock offset (espicially at stock ride height), 245/45 should work fine. And the extra diameter/circumference seems to do a good job of correcting the stock speedometer error.

i bought 245/40 dunlop sport races... they kick ass... i could have gone with 255/40s which actually DO fit on the 7.5 wheel from a 2004 with no rubbing.

-Z

rim size has basically nothing to do with speedometer reading. Only the tire's outer diameter has anything to do with speedometer reading. This spec is given by all manufacturers as the revs/mile.

So do you mean 18" and 17" has the same speed reading :confused:

if you have to deal with snow and all.. I dono if I would choose something very wide... however, Im POSITIVE that you can put on a 255/40

So do you mean 18" and 17" has the same speed reading :confused:

Thats exactly what he means. 17" or 18" is the inner diameter (the hole) in the tire. The larger the inner diameter, the less sidewall, keeping the outer diameter the same. Different sizes have different diameters, think our norm is around 25" so if a tire has a diameter of 25", it doesn't matter what size rim it fits on.

You just need to adjust the section height. For example, a 245/40-17 has about the same diameter & circumference (& speedo reading) as a 245/35-18.

Of course the down side to larger diameter wheels is they are heavier (tires typically are the same wieght for a gvien width & overall diameter) and the ride is harsher with the shorter side walls. Also, 18" wheels & tires cost more than their 17" equivalents.

Thats exactly what he means. 17" or 18" is the inner diameter (the hole) in the tire. The larger the inner diameter, the less sidewall, keeping the outer diameter the same. Different sizes have different diameters, think our norm is around 25" so if a tire has a diameter of 25", it doesn't matter what size rim it fits on.

Thanks, i get it now. So it is the overall diameter of the wheel. :)

if you have to deal with snow and all.. I dono if I would choose something very wide... however, Im POSITIVE that you can put on a 255/40

So can i put 255/35 Pzero nero M+S on my 18x7.5" rim with no rubbing?

what is the widest possible tire to put on the 05 sti stock rims? without rolling the fender? and how wide if you do roll the fender?

So can i put 255/35 Pzero nero M+S on my 18x7.5" rim with no rubbing?

Do your wheels have the stock offset? Probably not.

See this for effect of different offset:
http://toy4two.home.mindspring.com/offset.html

what is the widest possible tire to put on the 05 sti stock rims? without rolling the fender? and how wide if you do roll the fender?

As stated elsewhere in the tread, 255 without rolling. Rolling only helps outside/fender interference, I don't think you'll have room on the inside/strut side to go any larger than 255. MAYBE 265, but I have never heard of anyone running 275s that didn't have them sticking out of wheelwell (ESP guys with very stiff coilovers).

If you want good snow performance specifically, as against generic winter performance, you need a smaller section, taller tire, with a very aggressive (as in chunky) tread pattern. The smaller width "digs" in more (higher lbs/sq. in on the ground), and combined with the much more aggressive tread, you will have the best traction you can get.

i have heard of 275's being run all around and even 285's being run all around at the scca nationals. now as for what the suspension setups were or whatever mods were made to the cars to make this work i couldn't say.

Here's the deal: I know all about "smaller tires being better for snow" but I would also like to go up in with for year round.

Pay attention rogerd.


slowstangguy - all those guys who are running the big tires for autox who I have any reliable info on are going the "stick out the fenders and use with stiff springs & sways to minimize rubbing" route to get them to work. I have heard rumors of guys running wide tires by doing a lot of wheel well mods or flaring, but I haven't actually seen them or even got much detail on exactly what they supposedly did.