318ti vs. other e36 rear tire size
 

Please don't take this as a "how big of a tire can i fit" thread. I just want to understand the limitations of tire fitment with regards to the dimensions of the different suspension that ti's run. I've seen plenty of threads discussing that standard e36 cars can run 245s without an issue.

So, in your experience, does the semi-trailing arm setup restrict wheel and tire options on the ti when compared with a standard e36? I understand that coil overs will require additional room, but I'm curious about standard suspension equipment here.

So reading over my post, perhaps I am asking "how wide a tire can I run" but I want to understand the limitations more than just a tire size.

thanks!

I run 245/40x17's all the way round for autocross. They fit, but just barely. Not a lot of extra room there. I didn't have to roll any fenders to get them to fit either. I am tossing the idea of some wheel spacers but think I may get some fender rub if I do. So, I am pretty sure that is about as big as you can go with the ti.

Look for rear tire posts by bluebimma. Tony has fit some massive tires in the back of his ti for his LS swap.

Dan_I has a pretty serious track ti and he flared his car to run bigger tires. Maybe look at his pre-flare setup.

I'm on stock sport suspension, running staggered M3 Contour wheels. 245/40/17 tire size in the rear, it fits but I did have to roll the right fender. For some reason, only the right gave me trouble, left fits perfectly. Not sure why.

Thanks for the replies. I'm thinking that when running 245s, that the specific tire and the wheel offset also play a big role. I was pretty surprised at the range of values when comparing section width and tread width on different tires at tirerack. I'm looking at running an 8.5" wheel Et37 and the tire I'm looking to run has a 9.5" section width and an 8.7" tread width. Other tires I've looked at have a wider tread width - 9" to 9.5".

Joe & Coyoteh, can you comment on offset and the specific tires you are running?

Spider - I'll search for bluebimma threads too.

Thanks!

Joe and I drive the same car
 

I believe our wheels are a 40 offset and we're running Bridgestone Re71r tires

teen_ti, not that it matters, but what is the width of the wheel you are running - 8 or 8.5? Looking at the specs for the RE71R for your size, the section width is 9.8" and the tread width is 8.6"

The rear wheel I've got is 8.5" Et37. I want to run a 235/40/18 BFGoodrich G-Force Comp-2 A/S on these. Section width is 9.5" and tread width is 8.7" The diameter of this tire is 0.6" taller than the RE71R in 245/40/17.

If you and Joe are able to run the 245 on Et40 without fender rolling, then there is a chance that I can run the 235/40/18 without issues.

As added information, the wheels that are on one of the ti's I recently purchased are 18x8 Et20. The guy was running 245/40/18 tires on there without rubbing, but I have no idea how. I've since switched to 225/40/18 at all corners. If the Et20 works, I guess the big concern would be rubbing of suspension components with the Et37.

Our wheels are 17x8 and I'm not sure an 18" tire with 40 series sidewalls will fit. We were running 225/50x16 last year and this year we went to the 17x8 and they REALLY fill up the extra space in there. I think with an 18 inch wheel and 40 series side wall, there will be too much tire diameter, i think width will be ok. Maybe look for a 30 series sidewall if possible?(don't even know if they exist!)

Joe, I'm running 225/40/18 without issues currently. I drove 2100 miles on this setup and didn't notice any rubbing.

Diameter of the 225/40/18 is 25" while the diameter of the 235/40/18 is 25.3". Your RE71Rs are 24.7" in the 245/40/17 size which is the exact diameter of the stock 205/60/15 tires.

All in all, I would be adding about 8mm from the center of the axle to the top of the tire from the stock configuration. Suspension is the standard sport. I'm hopeful that .3" won't cause problems. I was more concerned with the outer edge of the tire clearance to the rear fender since it's a full inch larger than the stock configuration.

245/40-17 ET 47. Style 68 staggered. 235/45-17 up front


Sent from my iPhone using Tapatalk

Black, good to know. No fender rolling?

Nope. All fit fine with no rolling and I am also dropped a bit


Sent from my iPhone using Tapatalk

Black - especially good to know! Thanks for sharing.

My tires measure 24 1/4" in diameter, I am also running H&R "race" springs so the car rides a bit lower than stock. I have not had to roll any fenders and even under hard cornering, it doesn't seem to rub. However, on the way home from our last autocross, I left the big tires on and threw the 16's in the trunk and they did rub on the drive home with the extra weight in the back.

Joe - wow, quite a difference from the manufacturers spec on the RE71R and what you are measuring. I'll chalk that up to not always trusting what the manufacturer puts on paper. I'm not planning on lowering the car, but I do have the sport suspension which is a little lower than stock. I'm hopeful that the 235/40/18's will work out in that configuration. I'm not hell bent on 18's - in fact, I have a decent set of 17" Mille Miglia MMII-2 wheels that would be just fine. But these 18" wheels i just picked up were too good a deal and I already have relatively new 225/40/18 tires. Buying 2 235's is more economical than buying 4 new tires for the 17's. If I ever get into autocrossing, I'll go for the 17's for certain with sticky summer tires. Thanks for your info and advice.