Help with C5 wheel sizes
Thread Starter
Burning Brakes
Joined: May 2009
Posts: 1,014
Likes: 7
From: Ft Wayne IN
Help with C5 wheel sizes
OK, I am restoring some C5 Magnesiums 17-18" and what to get the widest possible rubber on each and maintain some sidewall for drivability so it doesn't ride like a rock. I am going with the Conti DW's.
Is it important to maintain the same overall diameter front and back so it doesn't affect the ABS or the wheel slip sensors?
If the ABS isn't an issue should I keep the same overall dia. the same or keep the sidewall height on each wheel the same i.e. the front being 1/2" overall shorter than the rear?
Will a 265/40/17 work on a 8.5" wheel?
Will a 295/40/18 work on a 9.5"
The chart on Tire rack says they are both 1/2" shy for recomended wheel size. I think Idealy I will end up with 255/45/17 = 26" dia,
and 285/40/18 = 27" dia.
or to keep the same dia. overall I would need 285/35/18 = 25.9 dia. in the rear.
I am confused on which would look correct
PLEASE HELP MAKE UP MY MIND! At close to $1,000 for tires I don't want to screw this up Thanks!
Is it important to maintain the same overall diameter front and back so it doesn't affect the ABS or the wheel slip sensors?
If the ABS isn't an issue should I keep the same overall dia. the same or keep the sidewall height on each wheel the same i.e. the front being 1/2" overall shorter than the rear?
Will a 265/40/17 work on a 8.5" wheel?
Will a 295/40/18 work on a 9.5"
The chart on Tire rack says they are both 1/2" shy for recomended wheel size. I think Idealy I will end up with 255/45/17 = 26" dia,
and 285/40/18 = 27" dia.
or to keep the same dia. overall I would need 285/35/18 = 25.9 dia. in the rear.
I am confused on which would look correct
PLEASE HELP MAKE UP MY MIND! At close to $1,000 for tires I don't want to screw this up Thanks!
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
You can pick any size you want that will fit. It wont upset the ABS.
My personal preference is to get tires that match in sidewall height. If you get ones that match overall diameter than the rear is going to have a smaller side wall and look weird. The stock tires are 25.7" diameter for reference.
The OEM tire size for a C5 would work well also
245/45/17 front
285/40/18 rear
My personal preference is to get tires that match in sidewall height. If you get ones that match overall diameter than the rear is going to have a smaller side wall and look weird. The stock tires are 25.7" diameter for reference.
The OEM tire size for a C5 would work well also
245/45/17 front
285/40/18 rear
Last edited by Kubs; Jul 26, 2012 at 06:29 PM.
Thread Starter
Burning Brakes
Joined: May 2009
Posts: 1,014
Likes: 7
From: Ft Wayne IN
Wouldn't the 245/45/17's be a little narrow if I wanted to autocross, etc.?
Also I am assuming it's the middle number i.e. 45 that dicatates the sidewall height? As long as I stay with the same (aspect ratio) or middle number, the side walls will have look the same ?
Can I get away with 45's in the front and 40's in the rear would it be a noticable difference?
Thanks for you help
OOOPS! I just realized the stock sizes have different aspect ratio's. I know that all changes with the first mumber and thats where I get confused. I wish they had sidewall heights in the specs.
Also I am assuming it's the middle number i.e. 45 that dicatates the sidewall height? As long as I stay with the same (aspect ratio) or middle number, the side walls will have look the same ?
Can I get away with 45's in the front and 40's in the rear would it be a noticable difference?
Thanks for you help
OOOPS! I just realized the stock sizes have different aspect ratio's. I know that all changes with the first mumber and thats where I get confused. I wish they had sidewall heights in the specs.
Last edited by C4vettrn; Jul 26, 2012 at 06:50 PM.
Le Mans Master
Joined: Oct 2007
Posts: 9,682
Likes: 3,434
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
If you are autocrossing you can go a little wider if you want. I would go no more than a 265 on the front.
I will help you with the tire size questions. The aspect ratio is just that, a ratio. Just because two tires have the same number for an aspect ratio does not mean they have the same sidewall height. Lets use the 245/45/17 as an example. The first number is the width of the tire in millimeters. 275mm is equal to 9.64 inches. The second number, or aspect ratio, is the percentage of that width that makes up the sidewall height. 245 x 0.45 = 110mm or 4.34 inches. This is the height of ONE sidewall. The final number is the rim diameter that the tire fits. In this case its a 17 inch wheel. To find the total height of the tire, multiply the sidewall height by 2 and add the wheel diameter.
(4.34 x 2) + 17 = 25.68 inches.
Also, lets look at a 315/35/17. The aspect ratio is 35 (smaller than the tire above) but:
(315 x 0.35)/25.4 = 4.34 inches (the same height as the 245/45/17 tire, which also means it has the same overall diameter.)
I hope this helps.
I will help you with the tire size questions. The aspect ratio is just that, a ratio. Just because two tires have the same number for an aspect ratio does not mean they have the same sidewall height. Lets use the 245/45/17 as an example. The first number is the width of the tire in millimeters. 275mm is equal to 9.64 inches. The second number, or aspect ratio, is the percentage of that width that makes up the sidewall height. 245 x 0.45 = 110mm or 4.34 inches. This is the height of ONE sidewall. The final number is the rim diameter that the tire fits. In this case its a 17 inch wheel. To find the total height of the tire, multiply the sidewall height by 2 and add the wheel diameter.
(4.34 x 2) + 17 = 25.68 inches.
Also, lets look at a 315/35/17. The aspect ratio is 35 (smaller than the tire above) but:
(315 x 0.35)/25.4 = 4.34 inches (the same height as the 245/45/17 tire, which also means it has the same overall diameter.)
I hope this helps.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
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From: South Dakota
The stock C5 sizes are:
245/45/17 front
275/40/18 rear
You can go a little wider with the ones you suggested.
255/45/17 front
285/40/18 rear
These sizes will fit the stock C5 base & magnesium (17x8.5 and 18x9.5) wheels. They will also fit the C5 Z06 (17x9.5 and 18x10.5) wheels. I have them on my C5 now on Z06 wheels. I like them and think it is a good setup. Note that they have the correct stagger of about 1" taller in back to keep the C5 active handling happy. The C4's didn't originally have this stagger, so it will sit higher in back than stock.
I put them (C5 wheels and tires) on my '94 and was not pleased with the ride height change. It felt too high in back and I went back to the C4 sizes.
Good luck with your choice. I like the magnesiums too. I have a set on my FRC.
A couple of pictures to help show the sizes.
255/45/17 front and 285/40/18 rear
C5 245/45/17 front and 275/40/18 rear. The rears are about an inch taller.
245/45/17 front
275/40/18 rear
You can go a little wider with the ones you suggested.
255/45/17 front
285/40/18 rear
These sizes will fit the stock C5 base & magnesium (17x8.5 and 18x9.5) wheels. They will also fit the C5 Z06 (17x9.5 and 18x10.5) wheels. I have them on my C5 now on Z06 wheels. I like them and think it is a good setup. Note that they have the correct stagger of about 1" taller in back to keep the C5 active handling happy. The C4's didn't originally have this stagger, so it will sit higher in back than stock.
I put them (C5 wheels and tires) on my '94 and was not pleased with the ride height change. It felt too high in back and I went back to the C4 sizes.
Good luck with your choice. I like the magnesiums too. I have a set on my FRC.
A couple of pictures to help show the sizes.
255/45/17 front and 285/40/18 rear
C5 245/45/17 front and 275/40/18 rear. The rears are about an inch taller.
Last edited by QCVette; Jul 26, 2012 at 08:21 PM.
Thread Starter
Burning Brakes
Joined: May 2009
Posts: 1,014
Likes: 7
From: Ft Wayne IN
Thanks for the help guy's
Is anyone else having any handling issues with the back higher than stock?
I am currently lowered about 3/4" all around and still have some adjustability left in the rear. One inch taller tires would creat a 1/2" raise in the rear I assume. I think I can drop the back another 1/4" and help it out some without looking funny.
Is anyone else having any handling issues with the back higher than stock?
I am currently lowered about 3/4" all around and still have some adjustability left in the rear. One inch taller tires would creat a 1/2" raise in the rear I assume. I think I can drop the back another 1/4" and help it out some without looking funny.
Le Mans Master
Joined: Oct 2007
Posts: 9,682
Likes: 3,434
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thanks for the help guy's
Is anyone else having any handling issues with the back higher than stock?
I am currently lowered about 3/4" all around and still have some adjustability left in the rear. One inch taller tires would creat a 1/2" raise in the rear I assume. I think I can drop the back another 1/4" and help it out some without looking funny.
Is anyone else having any handling issues with the back higher than stock?
I am currently lowered about 3/4" all around and still have some adjustability left in the rear. One inch taller tires would creat a 1/2" raise in the rear I assume. I think I can drop the back another 1/4" and help it out some without looking funny.
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