Will a 345/25/21 work without mods or issues?
Thread Starter
Drifting
Joined: Nov 2004
Posts: 1,623
Likes: 1
From: Gurley, Alabama
Will a 345/25/21 work without mods or issues?
A nearby guy has a set of signature brand wheels (20x9.5 fronts and 21x12.5 rears) for sale. He’s running 275/30/20 Michelins on the front and 345/25/21s on the rear. Says the front plastic had to be slightly trimmed but the rears fit perfectly. His car has a bunch of mods but I’m trying to avoid all the check engine lights etc if I purchase them. My intent was to change the front tires back to 255/30/21 but wondering if I can reuse the 345/25/21s since they are practically new.
With the above said, I thought I read somewhere on here or heard that larger tires would cause problems… something to do with the various sensors?? Thanks and look forward to your feedback.
With the above said, I thought I read somewhere on here or heard that larger tires would cause problems… something to do with the various sensors?? Thanks and look forward to your feedback.
Melting Slicks
Joined: Aug 2022
Posts: 2,784
Likes: 3,566
My first thought is that I would be hesitant to increase the rear contact patch (+40mm in width) relative to the front (+10mm in width). The sizes he has on there are just about an even percentage increase in front and rear contact patches. If you go back down to a 255, all things being equal, you're looking at a 13% increase in rear contact patch against a 4% increase in front. This will encourage more understeer, which the C8 has a bit of as is. That said, the last thing most guys going with 20/21 setups are concerned with is actual driving dynamics, so you do you. It will work.
Thread Starter
Drifting
Joined: Nov 2004
Posts: 1,623
Likes: 1
From: Gurley, Alabama
Thanks for input. Do you think I’d get any issues out of height difference? Other than just the speedometer being slightly off? Trying to avoid check engine lights and various codes.
My first thought is that I would be hesitant to increase the rear contact patch (+40mm in width) relative to the front (+10mm in width). The sizes he has on there are just about an even percentage increase in front and rear contact patches. If you go back down to a 255, all things being equal, you're looking at a 13% increase in rear contact patch against a 4% increase in front. This will encourage more understeer, which the C8 has a bit of as is. That said, the last thing most guys going with 20/21 setups are concerned with is actual driving dynamics, so you do you. It will work.
Melting Slicks
Joined: Aug 2022
Posts: 2,784
Likes: 3,566
Height difference is negligible. +2.2% in the rear and +0.8% in the front (I'm assuming you had a typo in your OP and meant 255/30R20 is your intent). You won't get any codes.
Last edited by combatninja; Feb 20, 2023 at 06:58 PM.
