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255/35/18 vs 255/40/17 WIDE tire setup

34K views 64 replies 13 participants last post by  goforbroke 
#1 ·
I’m trying to get a little insight on running these tire sizes regarding fitment. I know the 17’s will fit lots of info regarding 255/40/17 but not much info on 255/35/18. This is going to be my daily driver setup and my autox/track day setup. This is going to be a square tire setup no stretching tires going on. I’m going to be running CCW wheels in either 17x9 or 18x9 in a 40 or 45mm offset. I know the fenders will have to be rolled but I’m trying to avoid pulling the fenders at all cost since after all this is supposed to be a functional daily driver setup. Camber settings I’m going to try a few different setting until I can find the happy medium with handling and tire wear. My car is not going to be slam but with 1.5-2.0” drop all around.


With the 255/35/18 tire with 18x9 wheel in 40mm offset.
With the stock 215/50/17 with 17x7 in 55mm offset.

The rim will be 10 mm closer to the strut and poke out 40mm more than before.

I’m worried about making contact with the struts, but with 255/40/17 with the 17x9 wheel it has the same strut clearance of 10mm but I haven’t read anyone having clearance issues. I came across one guy mentioning he repeated kept hitting his struts with 255/35/18 tire and 18x9 wheels. Maybe he was lowered too much???

I can crunch numbers until the sun comes up, but real world experience always comes into play. Is the 18’s going to cause a bunch of rubbing issues for daily driving? Or am I going to have to run the ride height so high I don’t rub and my car looks like a 4x4…:smash:
Are the tires going to look too big in general with my conservative ride height?
So is anyone running this tire and wheel size that can provide some insight.

All of the info I came regard across were from threads many years old. I would PM the posters but they haven’t logged in to this site for many years. One helpful thread.

http://www.tsxclub.com/forums/1st-gen-wheels/57694-how-wide-can-we-go-18s-255-35-18-18x8-5-45-a.html
 
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#3 ·
Have you read the HeelToe/Marcus TSX build thread on this forum and on the Heeltoe website?

HTSpec TSX Redeux: Part 4, New old wheels - HeelToe Automotive

He was running 17x9 +48mm, 255/40R17 tires on his lowered TSX with minimal issues.

He is going to 18x9 +38 with 245/40R18 tires.
245's are a little narrow for 9" wide wheels but they seem to look fine in the pictures.
Since his 18" wheels have less offset (will stick out more), he has to go to narrower and taller tires.

255/40r17 and 255/35R18 tires are nearly identical in height and width.
They should fit identically on 17x9 and 18x9 wheels with the same offset.


For any kind of track use, I recommend 17" wheels. 255/40R17's are an excellent fit on 9" wide wheels.
Square sidewalls, no stretch, no bulging, for maximum tire performance and handling.
Plus there are a ton of tires choices in 255/40R17's.
That's what I run on my '89 5.0 Mustang.
 
#4 ·
Yeah I knew of Heeltoe's build with the 17s but I didn't know about the new 18" wheel setup. Interesting setup but 245s are a little narrow on 9" wheel but nothing worry about.

I'm going to end up running a 45mm offset to clear the 255s. I was trying to keep the rolling diameter relatively close to stock which is why I opt for the 255/35/18. A little concerned about about the 35 series because they don't provide much protection, but I believe a. 40s tire will be too tall.

Running 17s would be the easier way out along with the most cost effective and rational. If it was a huge weight penalty with the 18s I wouldn't do it but the 17s and 18s in the 3 piece CCW are very close in weight. Doesn't factor in tire weight though.
 
#5 ·
Do you have to run 255/35? Why not try a wide 245/40? I have 235/40/18 Falken Azenis RT615 on my 18x8.5 +35 Regamasters and they fit pretty square. If you are running 18x9 +45 wheels, a wide 245/40 would fit nicely. Plus, a 40 series a way more comfortable than a 35 series unless you don't care. Roll everything flat and cut the fender liners and you should be good. You'll be looking at 2-2.5 degrees with a 245/40/18. All comes down to your ride height.
 
#6 ·
I'm not opposed to running 245 series but I would like to fit the largest tires possible on the car without crazy mods. Also if I'm running a 9" wide wheel my plan has always been to run a 255, but will see. Totally forgot about the comfort level of a 40 series compared to a 35 series I'm guessing it will make a slight difference.
How did you come up with 2.0-2.5 degrees of camber.
 
#9 ·
Leave the big negative camber to the ricers and posers.

Running more than -2.0 degree camber with wide tires will really handle poorly and wear the tires out quickly.
I wouldn't even go more than -1.0 degrees front or -1.5 degrees rear.

Also don't forget that tire aspect ratio is just that, a ratio or percentage.
It's dependent on the tire section width.

You can't say that a 40 series tire will have more sidewall than 35 series tire. It's dependent on the tire section width.
 
#10 ·
I have zero intentions of running excessive amounts of camber. I only build and drive functional cars.
All things being equal such as a 255 tire vs another 255 tire of the same manuf a 40 series tire is going to have more side wall then a 35 series tire.

I looked at a car yesterday with 215/35/18 and the side wall was basically gone, while the 255/35/18 I've seen on Evo's, M3's, STI's and etc look pretty substantial probably due to the aspect ratio.
 
#12 ·
Haha that's the very reason why I plan on trying a few different camber settings.

I have a 1900lb autox civic I run in SM with 225/45/13 Hoosiers so I know a little something about setting up a car, but this 3300 lb sled is knew to me. Especially since I don't plan on making it unfriendly to drive every day.
 
#14 ·
So I'm starting to think a 245/40/18 is going to make more sense then a 255/35/18 my area is riddled with pot holes and running a 35 series tire is asking for trouble.
It's interesting though I've only found a handful of people running 245/40/18, not a very popular setup because everyone is into the whole stance ordeal I guess....

This Dart guy is, he chopped the photo though to lower his car.
http://www.tsxclub.com/forums/1st-gen-wheels/36451-black-wheels-w-carbon-gray.html

And this other dude as well.
http://www.tsxclub.com/forums/824239-post1.html

The sidewall height difference between a 255/40 and a 245/40 is a meager 4mm.

Are the the 255 really going to look that much bigger??? OR cause figment issues with 45mm offset on a 9" wheel.
 
#15 ·
I've decided I'm going to run 245/40/18. I know most of you guys done care but somebody might need the info at a later date and time.
There is a 3-4 week lead time on the wheels so I'll let you guys know how they fit along with some pictures. My suspension should be on the car before then so I'll get that sorted out.

I have a E350 Wagon with guess what.......245/40/18s on it. Of course I just realized this during the weekend. :tardsmash:
So I'm going to test fit them.
 
#18 ·
I was looking forward to running a 255 series as well, but after doing some more research and looking on tirerack some 245 series tires are actually wider/have a bigger contact patch then a 255 series. At least it will be an option later on down the line since I plan on running 18's. Riding around on 35 series sidewalls doesn't excite me and I know lots of people do it, but it's not for me.
I'll grab some cheap light weight 17's later on I can abuse on the track..lulz

18x8.5 +30 should fit fine, but it all depends on what size tire and drop. You guys and these low offsets...:p
 
#19 ·
215/50R17 25.5" diameter Stock TSX tire.
255/40R17 25.0
255/35R18 25.0
245/40R18 25.7

245/40R18's are significantly taller than the 255/40R17's and 255/35R18's.
 
#20 ·
You're right the stock tire 215/50/17 is 646.8 mm in diameter.
While the 245/40/18 is 653.2 mm in diameter.

So we got a difference of 6.4mm. Any small difference I have can be corrected with my Flashpro. It's going to change my gearing a little but hardly anything I will feel.

I might get ballsy and run a 255/35/18 if my test tires look like a 4x4 even with a drop.
 
#25 ·
^That is one of the most arguable subjects when it comes to tire wear..hehe.

My suspension arrived finally and I should have time to install it this weekend hopefully. Still haven't rolled my fenders yet but I'm going to see if my AMG wheels fit regardless. The offset looks pretty high but will see.
 
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