Best Tire Size for 18x8.5 Wheels

Hi all.

I was wondering if anybody had a good suggestion as to which tire size would be optimal for 18x8.5 (+48mm offset) wheels on a Legacy GT with stock suspension. I'm looking at getting a set of Rota G-Forces and I've seen some conflicting information about the tire sizes. Wheeldude's tire guide suggests 235/40 as the best size to fit without rubbing. Is there a better choice for a daily-driver?

Not that i've seen I will be pulling the trigger on these exact wheels soon in charcoal grey. Looks like im going to be getting the Falken azenis rt-615 in 235/40R18 and have only heard good things about them in the summer because these will be my dedicated summers. Cheers to the G-forces though

I'm having a hard time finding any definite information about the fit with 18x8.5" wheels and stock suspension - sounds like I should be more worried about rubbing on the suspension than the fenders.

I found this:

 

Just follow my first post about tire sizes. Unless you are going to get some aftermarket shocks or coilovers that uses a small diameter spring perch, you wont be able to any larger than:

 

25.5" overall tire diameter for a GT or 2.5i sedan

25.6" overall tire diameter for the Spec B

27.2" overall tire diameter for the Outbacks

 

According to the 1010tires calculator, 235/40R18 would result in an overall diameter of 25.4" - getting awfully close to Xenonk's limit. It would also result in the speedometer reading 3.2% too slow. 235/35 and 245/35 would be much closer to stock (24.47"/24.75" overall diameter), with the downside of having shorter sidewalls.

I highly doubt that 235's will rub on stock ride height considering people that are dropped for the most part don't rub. If you go any wider you will have roll the fenders. 235/35, I have found even less tires in this size compared to 235/40 also I believe that 35's are to thin(not width wise). Like i said im going to be getting g-forces 18X8.5 on 235/40R18 on stock suspension (as long as it doesn't look like a monster truck) and I'll tell you if they rub or not!

you should be fine with the 235/40 18, but I used a 245/35 18 since it has more grip and is closer to stock overall diamter.

you'll have no suspension clearance issues with the 8.5 +48 (I ran that too).

 

For a daily, get some 18x7.5 or 18x8 with 225/40 18 and call it a day. you don't need the extra grip or weight from the wheels or tires.

I have 18x8's lowered a decent amount and I run T1R 235/40/18 tires. I only have a very slight RUB when fulling turning the wheel left or right at parking lot speeds.

 

Other than that there is no rubbing unless I have a full car on a bumpy road.......

255/35/18

you should be fine with the 235/40 18, but I used a 245/35 18 since it has more grip and is closer to stock overall diamter.

you'll have no suspension clearance issues with the 8.5 +48 (I ran that too).

 

On an entirely stock suspension?

 

For a daily, get some 18x7.5 or 18x8 with 225/40 18 and call it a day. you don't need the extra grip or weight from the wheels or tires.

 

Unfortunately, the G-forces are not available in 18x7.5 or 18x8. I wonder how much of a difference the weight will make... Looks like the stock setup is ~42.5lbs for wheel & tire. I can't find any definite weight for the 8.5" wide G-force, but if it's ~21lbs, the G-force with Yokohama S.drive would be about 45.7lbs. 3.2lbs of extra unsprung weight on each corner.

i was running 18x8.5 SSR professor SP1's on 235/40/18 falken ziex 912's with no rubbing issues at all on stock suspension. it does give it a slight lift on the overall tire height though.

i was running 18x8.5 SSR professor SP1's on 235/40/18 falken ziex 912's with no rubbing issues at all on stock suspension. it does give it a slight lift on the overall tire height though.

 

Pics???

 

 

 

Flavio Zanetti

Boston, MA

255/35/18

 

Baller

^with rolled fenders and the right suspension parts, that size will fit without rubbing.

245/35/18.

 

i have spoken

245/35/18.

 

i have spoken

 

And lo, it is decided. http://sc2pod.com/forum//images/smilies/smiley-worship.gif

I want to run 245/35/18 on my 18x8 next . I learned this from Xenonk years ago. Pretty close to stock diameter and decent rim protection depending on the tire.

^I run this size. fits fine.

245/35/18.

 

i have spoken

And the Xenonk spake, saying, "245/35/18 shall be the number thou shalt count, and the number of the counting shall be 245/35/18."

 

these are the 18x8.5" SSR professor SP1's on 235/40/18 falken ziex 912's on stock suspension

FYI...245/40 does not fit. I'm still rolling/pulling.

Well I got my 18x8.5" +48 wheels and 245/35R18 tires on the car tonight. I haven't gotten a chance to actually drive it (won't til tomorrow). The clearance in the front seemed very tight but they did seem to fit.

 

The bigger question I have is that the front wheels now protrude about 3/8" from the fender. I suppose that might be unavoidable with the wider wheels and +48 offset?

post pix when u get the chance

ya, was gonna say, 245 would work great. that's what came on my 08 STI with 18x8.5 rims.

post pix when u get the chance

 

Here's the front-right wheel seen from above the fender:

 

http://www.smugmug.com/photos/539421692_BN3Pj-L.jpg

 

You can really see how it protrudes.

 

And a couple more:

http://www.smugmug.com/photos/539436967_bfhyV-L.jpg

http://www.smugmug.com/photos/539436754_VXoW2-L.jpg

time to roll/pull the fender.