tedboss1

I,m trying to decide on what wider tires I should use on my factory 10-inch wheels.
If any of you tried this combination;
305/30R21 or
315/30R21.
I'm looking at Michelis Pilot 4S.
The front will remain stock 265/40R21.
I would like to avoid any problems with the tires rubbing or needing a spacer.
My car is a stock 2019 GLC63S
Thanks for your help.

streborx

0.4" difference -- from how far away can you tell?

tedboss1

Can anyone share their experience with either 305 or 315 rear tires install?
Yoy help will be appreciated.

Bank$

What's up Tedboss I got yelled at by my tuner for going too much outside the % variation for the AWD system. They are very picky and car wear out the transfer case if your wheel diameter is too far off from the stock setup. Can you run a 305/30 or 315/30 and it work? Yes many have. But, longer term it could cause issues just FYI.

I'd recommend going with a 305/35/21 - it's less than a 1% difference. Check out the calculator here for changes in wheel diameter: https://www.calculator.net/tire-size-calculator.html

Our stock tire rear tire size sucks no super sticky tires (DR, autox) available in 20 or 21.

tedboss1

Bank$.
I like your recommendation for going with 305/35/21 tire.
One problem. I was not able to find this size in Pilot Sport 4S tire to match the stock front.
Is 4S even made in this size?

radride

The factory tires on the front is stretched and the tire on the rear is already bulgy at 295. You need wider wheels to run a 305 or it won't look good imo.

R.K.