Z 51 rims

[tnovot]

Can anyone tell me what is the advantage of Z51 rims for an earlier C4? The Z51 rears are 9.5 “ wide as opposed to the 8.5 “ fronts as well as all rims on the base non-Z51 cars.

They would hold a slightly greater volume of air and the sidewalls would be a little straighter because of the tire beads being farther apart but being on the rear only, I can’t see where it would help steering. The OEM tire size is the same for all 16” rims so there is no advantage as far as tread width.

Only thing I can think of is that they might keep the rear end from sliding out on hard cornering because of a straighter sidewall. Is there more to the story?

Thanx for any and all replies.

Terry

 

[Edmond]

Terry,

Someone here answered that question before. I'm sorry to say that I can't remember what that answer was but at least you get a bump!

 

[tigmaned]

more on the road??

i know the tire companys love it, one tire and rim only fits in one place. and no way to rotate.

 

[tnovot]

Terry,

Someone here answered that question before. I'm sorry to say that I can't remember what that answer was but at least you get a bump!

Thanks. I did a search of Z51 wheels and found a lot of chatter and some good info but nothing which answered this specific question. Hopefully someone will come up with the answer.

 

[Jeroenvgfn]

Sorry I cannot help you with an answer , but the question is very interesting.

I am posting this question on the European forum too, maybe the answer is taken to this side of the pond.

 

[tnovot]

Sorry I cannot help you with an answer , but the question is very interesting.

I am posting this question on the European forum too, maybe the answer is taken to this side of the pond.

Thank you for any information. I recently replaced my stock '84 Z51 wheels with a set of highly polished '87 base 8.5 wheels and wonder what, if anything, I lost. Whatever it may have been, the gain in appearance is well worth it.
My new Falken tires have improved the ride and possibly the handling regardless of any changes attributed to different wheels.

 

[Jeroenvgfn]

according to my knowledge the early Vettes have 4*8,5" standard and the Z51 4*9,5" and both version wear the same tires

the later Vettes have front 8,5" and rear 9,5" standard and 4*9,5" with Z51
but also the standard has a different tire size installed on 8,5"

 

[flrider]

I read somewhere long ago when the c4's came out the 9.5 wheels were installed on the lateral g-force test car to achieve the 1g rating. Did not make the 1g with the 8.5 wheels up front. In Chevy literature someplace.

 

[tnovot]

according to my knowledge the early Vettes have 4*8,5" standard and the Z51 4*9,5" and both version wear the same tires

the later Vettes have front 8,5" and rear 9,5" standard and 4*9,5" with Z51
but also the standard has a different tire size installed on 8,5"

According to the 2003 Corvette Black Book, '84 base wheels were 8.5's and the Z51 had 9.5's on the rear only. This is how my '84 was equipped so I believe the info to be accurate.
The Black Book also says that for 1985 through 1987, a change was made for Z51 cars to put 9.5's on all 4 corners. It can be assumed by lack of contrary information, that the 85-87 base cars still had the 8.5 wheels. All tire sizes were the same at 255-50-16. In 1988, the Z51 went to 17" wheels.
Nothing was mentioned about whether the exported cars had different sized wheels and/or tires.

 

[tnovot]

I read somewhere long ago when the c4's came out the 9.5 wheels were installed on the lateral g-force test car to achieve the 1g rating. Did not make the 1g with the 8.5 wheels up front. In Chevy literature someplace.

That would explain why they made a change in 1985 to put 9.5's on the front as well as the rear of Z51 cars. And, you may have just answered my original question.
I am now convinced that the advantage of the wider rim is to give the sidewall more support during cornering. Since I don't race my car on any kind of oval or roadcourse I didn't really lose much by giving up my stock '84 Z51 wheels for a polished set of base 8.5's. I traded handling for pretty and I am happy with that.
Thanx to everyone for your replies, comments, and information,
Terry

 

[Jeroenvgfn]

stupid me, I haven't thought of looking in the Black book :confused

I have a spare set of Z51 9,5 " in my garage which I am going to polish
and putting on a new set of tires next spring.

back will get the 255/50/16
front will get 235/55/16

I now have totally wrong tires on my vette, 225/60/16 which are original Mercedes tires.

I bought the Vette with them on 6 years ago, and despite my strong cornering these damn tires wouldn't wear out

never tried a burnout but since there are almost worn out they will be getting one shortly

 

[tnovot]

I have a spare set of Z51 9,5 " in my garage which I am going to polish
and putting on a new set of tires next spring.

back will get the 255/50/16
front will get 235/55/16

The polished wheels should look really good - nice contrast with the black.
Just a thought; if you were to put on all 255 50 16's and the wheels are all 9.5, you would at least be able to rotate tires front to back.

 

[Jeroenvgfn]

The polished wheels should look really good - nice contrast with the black.
Just a thought; if you were to put on all 255 50 16's and the wheels are all 9.5, you would at least be able to rotate tires front to back.

yeah I know, but I like the contrast It makes the rear wheels even meaner.
like with the ZR1

a friend of mine advised me to buy a set of ZR1 wheels and a quarter panel
together with a dash "power" key to create a 1989 ZR1 replica

but I will stick with saving money for a
Callaway SNAT or maybe a ZR1 SNAT .