Tire sizing questions
Thread Starter
Melting Slicks
Joined: Mar 2006
Posts: 2,599
Likes: 34
From: Grand Rapids Michigan West Michigan Crew
2015 C5 of the Year Finalist
St. Jude Donor '07-'08-'09
Tire sizing questions
Looking at new tires and have a couple questions on sizing. Im looking to get Pilot Super Sports in 275/35-19 and 345/30-19. According to my research the overall diameter of these tires are 26.6 front and 27.2 rear. From what I understand, in order to keep the TC/AH system from getting confused and messing up the rear tires have to me a minimum of 1/2 taller than the front. with this combo only being .1" past that minimum do i run the risk of throwing of the system down the road since we all know the rear tires are going to wear much faster than the front?
My other option is keeping the same tire in the rear (27.2") and going to a 30 series front which drops overall diameter to 25.6" or is that too much of a difference? I would like to have the extra rubber on the rim just to give me that little bit of extra cushion to protect the rim on the lovely pot-hole littered Michigan roads if possible!! Thanks!
My other option is keeping the same tire in the rear (27.2") and going to a 30 series front which drops overall diameter to 25.6" or is that too much of a difference? I would like to have the extra rubber on the rim just to give me that little bit of extra cushion to protect the rim on the lovely pot-hole littered Michigan roads if possible!! Thanks!
Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
Looking at new tires and have a couple questions on sizing. Im looking to get Pilot Super Sports in 275/35-19 and 345/30-19. According to my research the overall diameter of these tires are 26.6 front and 27.2 rear. From what I understand, in order to keep the TC/AH system from getting confused and messing up the rear tires have to me a minimum of 1/2 taller than the front. with this combo only being .1" past that minimum do i run the risk of throwing of the system down the road since we all know the rear tires are going to wear much faster than the front?
My other option is keeping the same tire in the rear (27.2") and going to a 30 series front which drops overall diameter to 25.6" or is that too much of a difference? I would like to have the extra rubber on the rim just to give me that little bit of extra cushion to protect the rim on the lovely pot-hole littered Michigan roads if possible!! Thanks!
My other option is keeping the same tire in the rear (27.2") and going to a 30 series front which drops overall diameter to 25.6" or is that too much of a difference? I would like to have the extra rubber on the rim just to give me that little bit of extra cushion to protect the rim on the lovely pot-hole littered Michigan roads if possible!! Thanks!
From what I have read... you can have a much larger diameter rear tire and thats ok.
Its only when your rear tire is close to or smaller than your front tire that you have issues.
Many of the folks that have Wide fender rear's run 345 sizes with no issues.
I am not exactly sure what front size they run, but I suspect its going to be 275/30/19.
Be careful going too large in the front or you will have tire rubbing issues.
Toque
Tech Contributor
Joined: Jan 2004
Posts: 20,030
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From: Wylie TX --> Less is More, except under the hood !
I know the rear tire must be 0.5" or larger diameter than the front.
So your saying that the rear tire "should" not be larger than 1.5" diameter compared to the front ?
It makes sense that if you go TOO big in the rear then it will take much more wheel spin before your car detects a traction control problem and turns that part on to protect you.
Thanks
Toque
Thread Starter
Melting Slicks
Joined: Mar 2006
Posts: 2,599
Likes: 34
From: Grand Rapids Michigan West Michigan Crew
2015 C5 of the Year Finalist
St. Jude Donor '07-'08-'09
The half inch larger minimum rear wheel diameter is a "rule of thumb". Some C5 owners claim they run the same size tires front and rear and have no problems with TC. Others have reported problems with only a 1/4" tire diameter delta. The 1 1/2: maximum delta is so that you still have TC in the event it is needed. If you go too large the TC will never come on when/if needed.
The .6 delta that you have with the first choice of tires should be fine...
If TC did become a problem as your rear tires wear out (for some reason rear tires on a vette wear out much faster than the fronts
) you can simply turn off TC and AH every time you drive the car.
The .6 delta that you have with the first choice of tires should be fine...
If TC did become a problem as your rear tires wear out (for some reason rear tires on a vette wear out much faster than the fronts
) you can simply turn off TC and AH every time you drive the car.
Im happy with my front tires so im not going to change the size there. I am having rubbing issues on the rear though. The tires rub on the inside on the frame when I hit a big enough bump. I ended up adjusting the rear shocks to a stiffer setting to get through the summer but I want the root cause of the problem fixed this spring so I am going to try and go one size narrower on back. Thanks for the input everyone!
