Tread Depth
Thread Starter
Drifting
Joined: Feb 2005
Posts: 1,311
Likes: 1
From: Los Angeles CA
Tread Depth
My apologies if it has been asked 101 times but what is the tread depth of the C6 Z51 tires when new and at what depth should one start thinking about replacing them? I know they "should" show the tread wear indicator but I am trying to plan out when based on my current wear rate I will need to replace them and I cant figure out the wear rate as I dont have the initial depth value
Le Mans Master
Joined: Feb 2000
Posts: 8,593
Likes: 1
From: Yorktown Heights NY
St. Jude '03-'04-'05-'06
The tread depth of the Z51 tires is 9/32" when new. Here's a link to the Tirerack page that lists the Z51 tire specs.
http://www.tirerack.com/tires/Spec.j...5YR9F1SPRCREMT
I would replace them at 4/32" although they are legal to 2/32".
Frank
http://www.tirerack.com/tires/Spec.j...5YR9F1SPRCREMT
I would replace them at 4/32" although they are legal to 2/32".
Frank
Last edited by Another Yellow; Dec 20, 2005 at 07:35 AM.
Drifting
Joined: Jun 2005
Posts: 1,837
Likes: 4
Originally Posted by Another Yellow
The tread depth of the Z51 tires is 9/32" when new. Here's a link to the Tirerack page that lists the Z51 tire specs.
http://www.tirerack.com/tires/Spec.j...5YR9F1SPRCREMT
I would replace them at 4/32" although they are legal to 2/32".
Frank
http://www.tirerack.com/tires/Spec.j...5YR9F1SPRCREMT
I would replace them at 4/32" although they are legal to 2/32".
Frank
But the lateral tread on the outer segment is less than this.
It may vary some by state, but most require 2/32" tread in at least 3 grooves. How this is measured and interpreted is up to the person inspecting it.
BTW, the non-Z51 tires have 11/32" tread when new.
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,703
From: Far NW 'burbs of Chicago
St. Jude Donor '13
Of course the tread is only significant on a wet road. You might be able to run them down to 2/32" if it's the dry season in LA. Just be REALLY careful if you get on wet pavement.
Racer
Joined: May 2005
Posts: 415
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From: Cocoa Florida
Originally Posted by Buffy
But the lateral tread on the outer segment is less than this.
It may vary some by state, but most require 2/32" tread in at least 3 grooves. How this is measured and interpreted is up to the person inspecting it.
BTW, the non-Z51 tires have 11/32" tread when new.
They were all 9/32" tread depth.
Drifting
Joined: Apr 2005
Posts: 1,746
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From: Upper St. Clair PA
St. Jude Donor '06-'07-'09
Originally Posted by Mocoso
Thanks for the replies guys... I dont think Ill go down to 2/32 but I may keep em once they hit 4/32 for track use...
Would like to get new wheels and tires for shows and everyday use, but will wait until there are more choices for tires. 
I'll burn up the runflats autocrossing and eventually get new treads for the stock rims.
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Drifting
Joined: Jun 2005
Posts: 1,837
Likes: 4
Originally Posted by jruss361
Measured all four of my non-Z51 tires on day one of ownership.
They were all 9/32" tread depth.
They were all 9/32" tread depth.
http://www.tirerack.com/tires/Spec.j...h=true&index=6
Racer
Joined: May 2005
Posts: 415
Likes: 0
From: Cocoa Florida
Originally Posted by Buffy
That's interesting, and I stand corrected. The Tire Rack shows shows 10/32" front and 11/32" rear - but spec sheets have been wrong before!
http://www.tirerack.com/tires/Spec.j...h=true&index=6
http://www.tirerack.com/tires/Spec.j...h=true&index=6
It got away from me on the C5 and wasn't bad enough at the time to get GM to replace the tires. Close but NO cigar.
At the time it also looked like I wore 25% of the tread off all four tires at 4200 miles. But the fact was I started with 2/32" less then th specs were quoting. I'd only wore off 1/32".
Burning Brakes
Joined: Nov 2005
Posts: 1,037
Likes: 126
St. Jude Donor '07
Originally Posted by Buffy
That's interesting, and I stand corrected. The Tire Rack shows shows 10/32" front and 11/32" rear - but spec sheets have been wrong before!
http://www.tirerack.com/tires/Spec.j...h=true&index=6
http://www.tirerack.com/tires/Spec.j...h=true&index=6
Team Owner
Joined: May 2004
Posts: 82,175
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From: McKinney TX
St. Jude Donor '21-'22-'23-'24
Because I had to have a RF tire replaced recently, I bought a tread-measuring tool. I used it to measure the amount of tread on the tires on a new 2006 Monterey Red non-Z51 coupe sitting on my local dealer's showroom floor. The front tires had 10/32 of an inch of tread. The back tires had 11/32 of an inch of tread.
The new tire (700 miles) on my car measured 10/32 in the 2 middle grooves and about 9.8 in the 2 outermost grooves.
Would there be any reason for the OEM non-Z51 tires on a new 2005 coupe to have a different amount of tread than a new 2006 coupe?
The new tire (700 miles) on my car measured 10/32 in the 2 middle grooves and about 9.8 in the 2 outermost grooves.
Would there be any reason for the OEM non-Z51 tires on a new 2005 coupe to have a different amount of tread than a new 2006 coupe?
Drifting
Joined: Jun 2005
Posts: 1,837
Likes: 4
Originally Posted by Driver_WT
OEM tires frequently have less tread than replacement tires. Saves a few bucks per car for the car manufacturer.
But it's funny that we have two direct measurements here, and they differ. It does suggest that there are two different tires, and maybe they ran low on the OEM version and threw in some of the aftermarket ones on the car with 10/32 and 11/32 tread.
Or maybe they changed them in mid-production.
I didn't measure my Z51 "supercar" tires when brand new, but working backward from the data I have it looks like the fronts were about 8.5 x 1/32" and the back about 8.9 x 1/32", which is a few percent under the 9/32" spec.
Racer
Joined: May 2005
Posts: 415
Likes: 0
From: Cocoa Florida
Originally Posted by SilverCoupe
Because I had to have a RF tire replaced recently, I bought a tread-measuring tool. I used it to measure the amount of tread on the tires on a new 2006 Monterey Red non-Z51 coupe sitting on my local dealer's showroom floor. The front tires had 10/32 of an inch of tread. The back tires had 11/32 of an inch of tread.
The new tire (700 miles) on my car measured 10/32 in the 2 middle grooves and about 9.8 in the 2 outermost grooves.
Would there be any reason for the OEM non-Z51 tires on a new 2005 coupe to have a different amount of tread than a new 2006 coupe?
The new tire (700 miles) on my car measured 10/32 in the 2 middle grooves and about 9.8 in the 2 outermost grooves.
Would there be any reason for the OEM non-Z51 tires on a new 2005 coupe to have a different amount of tread than a new 2006 coupe?
Safety Car
Joined: Jul 2001
Posts: 4,456
Likes: 6
From: Spicewood, Texas, USA TX-Texas
With this much conflicting data from actual measurements, it makes one wonder if Goodyear is shaving tread after molding to correct for minor out-of-roundness. Tread measurements at several locations around the tire would need to be compared. 
I have heard of this procedure being done, but I think it was like a last resort to save a tire. Discount Tire doesn't do it...if the tire can't be balanced within their maximum allowable weight, they reject the tire.
I have heard of this procedure being done, but I think it was like a last resort to save a tire. Discount Tire doesn't do it...if the tire can't be balanced within their maximum allowable weight, they reject the tire.
Drifting
Joined: Jun 2005
Posts: 1,837
Likes: 4
Originally Posted by JmpnJckFlsh
With this much conflicting data from actual measurements, it makes one wonder if Goodyear is shaving tread after molding to correct for minor out-of-roundness. Tread measurements at several locations around the tire would need to be compared.
I have heard of this procedure being done, but I think it was like a last resort to save a tire. Discount Tire doesn't do it...if the tire can't be balanced within their maximum allowable weight, they reject the tire.
I have heard of this procedure being done, but I think it was like a last resort to save a tire. Discount Tire doesn't do it...if the tire can't be balanced within their maximum allowable weight, they reject the tire.
I don't know about others, but I measure at three points around the circumference (as well as three points across). My tires vary between 0.004" and 0.016" around, or about 6% maximum. I'm willing to accept that as measurement error given that it's hard to get a really solid reading on the rubber. Which is why I take three readings and average them.
