gpatti

Can I go with a slightly bigger tire than the factory 225/40 18 and 295/30 18? Is there a pro or con?

NOTE:
- I just had H&R lowering springs installed, so it is roughly 1-1/4" lower.
- Going on BBS SR021 & SR022. 18x8 ET50 and 18x10 ET41, which I just bought
- Street use only on sunny days. I put about 500 miles a year on the car.
- Not opposed to spacers if needed. Essentially looking for a wider GT2 type of stance

Would love to get some feedback before I just get the factory size.

Thank you!

Carlo_Carrera

Just to be clear you're running a 10 inch wide wheel on the rear?

powdrhound

Your wheels are too narrow. Don't use those. They will NOT work.

WillyDaP

Please be cautious on blanket statements as simply checking a tried and true source ( TireRack ) shows that the sizes listed by the OP will work fine. I used just one tire ( Bridgestone RE71RS for an example and after checking the Specs it is showing a 10-11 inch wheel width for the rear using a 295 and 7.5 to 9 for the 225s in front. For reassurance call their Toll Free number and then punch in Ext. #4362 for Luke Pavlik, who I have known for over 24 years and he has advised a ton of racer friends ( he is a track rat and autocrosser himself ). Good luck , but my suggestion would be to check with Luke and you may find putting in a bit of negative camber will also help.

Bernard IV

Can he get larger barrels assuming those are 3 piece wheels?

nick49

From personal experience since '11 I've found it really important to have the diameters as close as possible between F & R. Too large of variance will tear up the viscous coupling in your front diff. I've also found when my car was RWD replacing worn out rears with new ones and 2/3 worn fronts, the traction control didn't like it and would sence a variance in wheel speeds from front to rear. This told the system a tire was losing traction when in fact it was not and to apply a brake to it. This happened a few times and is pretty scary at freeway speeds. I quickly replaced the worn fronts with new ones closer matching the new rear diameters. Problem solved! Take this into consideration.

gpatti

Yes, correct

alxdgr8

There is a front to rear circumference bias from the factory specifically to introduce a speed differential in the viscous center diff. Otherwise there would be no torque transfer until the rear axle slips.
You want to match the factory circumferences or at least the factory circumference difference. You don't want to make them the same.

Lazurus

A 10" rear wheel is a terrible idea. In fact, I've never heard of anyone either trying that or why they would. 11 or 12 is the way to go. There can be no advantage to running a smaller wheel size in the rear, even if you can.

If you're already using lowering springs? Just switch to a 12" rear wheel and you'll more closely approximate a "GT2" ride height and stance. You'll be lower in fact.

Carlo_Carrera

OK, first off you need wheels that are at least OEM width before you even think about going wider with the tires. 8 1/2 wide at the front and 11 at the rear minimum.

Once you have those wheels if you want to go wider than stock folks go with either a 235/40-18 or 245/40-18 at the front matched with a 315/30-18 at the rear.


Your car is AWD?

gpatti

WTF….. looks like I need to sell these wheels. I completely spaced. I had it in my head that the factory were 10” rear, but they are 11”. Back to the drawing board. Looks like I will have to sell these and look for new wheels first! Sure glad I posted this, I would’ve bought new tires, and been in a world of ****. My apologies for the runaround, but very much appreciate everyone’s help. Unfortunately, I don’t know how to end this with emoji of a screaming face with head about to explode…….

diverzeusy

wheel width. 10'' 11'' 0r 12' inch is of no relevance, why you would go 10'' inch however I do not know
. The main measurement as stated is the running diameter of the tires
check out
Alloy Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

simply enter factory spec in the 1st box and then your intended new tyre size in the second box,
Also once you have the wheels ready roll a front andrear together along a flat surface they should be very similar in distance covered, or meaning one should not pass the other by any significant margin.
get it wrong you will screw your viscous coupling

Lazurus

No one, OP included seems to know! But he did ask "Can I go with a slightly bigger tire than the factory 225/40 18 and 295/30 18? Is there a pro or con?" so in that regard it's relevant because he can certainly "go with a slightly larger tire" running 11" wheels ( 315-30-18 is ok and not stretched for *most* tires and at least running OEM twists it's fine ) and would also fit if running 12"s as then many commonly run on 315-30-18. Is a 225/40 stock front too narrow for anything but the OEM 8" wheels, I imagine so. As noted by others a 235/40 will work nicely on 8.5's or even 9"'s, if my memory serves. I never ran 9" front for long and went back to ( 8.5 X 12 ) and have always run 12" rears. I believe he realizes he erred with the 10" wheels. That sucks!

alxdgr8

The 10" wheel is great for running the winter spec 265. I've got some BBS SR for that reason.