tire/rim question
Thread Starter
Instructor
Joined: Mar 2012
Posts: 170
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From: NH
tire/rim question
I have a 93 coupe. The sticker on my door says I need 285/40/R17 for the rear and 255/45/R17 for the front. However, what is currently on my car is 4 275/40/R17. My question is, could the PO have just picked a compromise size and fit them to the stock rims so that he would be able to rotate them and make them last a bit longer or would the 275's not fit on stock rims? The rims look like the original sawblades. I know there is usually some flexibility as to what size tires will fit on a rim, but I also seem to remember seeing somewhere that there was an option for 275/40/17 on the 93 vette, I forget what RPO though and I would think if this was the case, my door sticker would reflect it. I am going to have to replace tires soon, and I dont want to order stock tire sizes if they are not going to fit any insight would be appreciated.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
The '93 was the first year to have the staggered
17 x 8.5 wheels with 255/45/17 tires front and
17 x 9.5 wheels with 285/40/17 tires rear.
The Z07 option had
17 x 9.5 wheels with 275/40/17 tires front and rear.
This is the size that had been used for all of the '88 to '92 cars.
The 275/40/17 or 285/40/17 fit fine on the 9.5 wheels. The tire charts also show a 255/45/17 tire can fit on a 9.5 rim.
For the 8.5 wheels the 255 tires are the factory size, but I have seen 275's on them too. Most tire charts don't list the 275 tire for a 8.5 rim, but a few such as the Goodyear GSC did.
You might want to take a look at your rims and see which rim widths you have.
17 x 8.5 wheels with 255/45/17 tires front and
17 x 9.5 wheels with 285/40/17 tires rear.
The Z07 option had
17 x 9.5 wheels with 275/40/17 tires front and rear.
This is the size that had been used for all of the '88 to '92 cars.
The 275/40/17 or 285/40/17 fit fine on the 9.5 wheels. The tire charts also show a 255/45/17 tire can fit on a 9.5 rim.
For the 8.5 wheels the 255 tires are the factory size, but I have seen 275's on them too. Most tire charts don't list the 275 tire for a 8.5 rim, but a few such as the Goodyear GSC did.
You might want to take a look at your rims and see which rim widths you have.
Team Owner
Joined: Sep 2003
Posts: 25,386
Likes: 2,740
The wheel width is cast on the back side of the wheel on your car and it will also have likely a seven or eight digit number cast on the back-side also for identification. The side wall appearance should be distinguishable for a 275 on an 8.5 vs a 9.5 also I would think!
Using a wheel/rim caliper on the extreme outside edge of an 8.5 wheel will display something near 9.5 and the extreme edges of a 9.5 will display something near 10.5 !
Last edited by WVZR-1; May 23, 2012 at 02:37 PM.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
There is also a visual difference between the 8.5 and 9.5 sawblades.
How deep the dish is shows up different between the two. Look at the section that is between the largest diameter of the "blade" and the farthest point to the outside of the car.. That smooth turned section is about 1/4" (just guessing at the measurement difference) deeper on the 9.5" wheels.
How deep the dish is shows up different between the two. Look at the section that is between the largest diameter of the "blade" and the farthest point to the outside of the car.. That smooth turned section is about 1/4" (just guessing at the measurement difference) deeper on the 9.5" wheels.
Team Owner
Joined: Sep 2003
Posts: 25,386
Likes: 2,740
There is also a visual difference between the 8.5 and 9.5 sawblades.
How deep the dish is shows up different between the two. Look at the section that is between the largest diameter of the "blade" and the farthest point to the outside of the car.. That smooth turned section is about 1/4" (just guessing at the measurement difference) deeper on the 9.5" wheels.
How deep the dish is shows up different between the two. Look at the section that is between the largest diameter of the "blade" and the farthest point to the outside of the car.. That smooth turned section is about 1/4" (just guessing at the measurement difference) deeper on the 9.5" wheels.
http://forums.corvetteforum.com/c4-p...-for-sale.html
Tech Contributor
Joined: Oct 2011
Posts: 525
Likes: 9
From: Annapolis MD
The '93 was the first year to have the staggered
17 x 8.5 wheels with 255/45/17 tires front and
17 x 9.5 wheels with 285/40/17 tires rear.
The Z07 option had
17 x 9.5 wheels with 275/40/17 tires front and rear.
This is the size that had been used for all of the '88 to '92 cars.
17 x 8.5 wheels with 255/45/17 tires front and
17 x 9.5 wheels with 285/40/17 tires rear.
The Z07 option had
17 x 9.5 wheels with 275/40/17 tires front and rear.
This is the size that had been used for all of the '88 to '92 cars.
My 92 had 17x9.5 sawblades and 275-40-17's all around.
I replaced them with a set of ZR1 a-mold replica staggers.
17x9.5 front, 17x11 rear.
275-40-17 Nitto NT05's front, 315-35-17 Nitto NT05's rear.
I'm happy.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
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Thread Starter
Instructor
Joined: Mar 2012
Posts: 170
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From: NH
So I imagine that all the rims being the same size is actually a good change over stock right? I will allow me to rotate front to back and make the tires last longer with only a slight compromise on the back tire width which 275 should be more than enough. Any reason why narrower tires up front would be better?
Tech Contributor
Joined: Oct 2011
Posts: 525
Likes: 9
From: Annapolis MD
So I imagine that all the rims being the same size is actually a good change over stock right? I will allow me to rotate front to back and make the tires last longer with only a slight compromise on the back tire width which 275 should be more than enough. Any reason why narrower tires up front would be better?
If you drive the car enough to need to rotate tires, that is a good strategy.
I don't... That is why I mounted staggers.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
The reason GM went to the staggered sizes was for the country club set that did not want the steering tugging on uneven pavement or rutted pavement. The huge positive camber in the cars plus the more narrow front tires=stable steering feel.
Note how the RPO Z07's all got 275's at all four even in 93-95 cars.
I swapped my FX3 suspension 93 to 275's from the staggered, and yes it does wander a bit more but not too much with close to stock alignment settings. I did a more "performance" alignment with Zero front toe, negative .5 degree at all four and about 6 degrees of caster in the front.
Yes, on rutted/uneven pavement it wanders a bit but it is more annoying than anything, not so much that I really even notice most of the time.
The improvement in handling is night and day, turn in is sharp and car has way more grip in corners as well as feeling WAY more neutral. Has a ton less under-steer.
I'm VERY happy with the 275's and my aggressive street alignment. Then again I'm NOT the country club set.
Note how the RPO Z07's all got 275's at all four even in 93-95 cars.
I swapped my FX3 suspension 93 to 275's from the staggered, and yes it does wander a bit more but not too much with close to stock alignment settings. I did a more "performance" alignment with Zero front toe, negative .5 degree at all four and about 6 degrees of caster in the front.
Yes, on rutted/uneven pavement it wanders a bit but it is more annoying than anything, not so much that I really even notice most of the time.
The improvement in handling is night and day, turn in is sharp and car has way more grip in corners as well as feeling WAY more neutral. Has a ton less under-steer.
I'm VERY happy with the 275's and my aggressive street alignment. Then again I'm NOT the country club set.
Thread Starter
Instructor
Joined: Mar 2012
Posts: 170
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From: NH
Looks like I have 9.5 in all around. Anyone have any recommendations on tires? I am going to keep the set up with 4x 275's and I think I may go with some all weathers just to be able to extend the driving season up in NH. I have noticed that there is a bit of wander, but it not that big a deal. Rubie, what are you running on there for tires with your aggressive alignment specs?
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Looks like I have 9.5 in all around. Anyone have any recommendations on tires? I am going to keep the set up with 4x 275's and I think I may go with some all weathers just to be able to extend the driving season up in NH. I have noticed that there is a bit of wander, but it not that big a deal. Rubie, what are you running on there for tires with your aggressive alignment specs?
I recommend the Continental Extreme Contact DW's, very good tire. Will be my next set for street driving duties. I'm getting a dedicated set for auto-x.