C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Considering upgrade wheels

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Old Apr 13, 2019 | 12:13 PM
  #21  
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good looking rims are kind of hard to find really from what i found, a lot of the new rims are not really my taste, i ended up buying the rims the previous owner had which are a zr1 replica i think, for the 91 model, they look decent but it is also pretty common. i really wanted a set of weld wheels but when i saw the price i about choked on my coffee, 2 grand for 1 rim, my wallet said not going to happen. i can show you what a 91 vert looks like with them if you want a visual. only pic i have now is one while it is up on jack stands which doesnt really show it well since the tires are hanging in the air
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Old Apr 13, 2019 | 01:09 PM
  #22  
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Originally Posted by MatthewMiller
9" is the minimum recommended wheel width for a 275/40 tire (9-11"). That will work - not ideal for best track times, but it will be fine on the street. This offset will work nicely.


Same as above, and the tire size could be 275/35r18 on the wide end, or a 245/40r18 on the narrower end. The latter is probably a better overall fitment for this width tire.


You'd need 1/2" spacers to run these wheels, which is fine to use. You may need longer wheel studs to use them, though. For tires, either 285/35r18 or 295/35r18. I'd go with the 285s.


This is kind of an opinion-based, pro/con decision. To my mind, if you jump to 18s and pay for new tires, go with the wider 10.5" tires and spacers. They'll look better and give better performance. Your car will stand out from most C4s that have narrower rolling stock. People will compliment your car without exactly knowing why it looks badass compared to other C4s. I don't think you gain anything by going to the 18x9. If you're going to stick with 9" width wheels, then you might as well stick with the 17" wheels and use the tires you already own. That's money you can spend on other things.
My instinct is to go with the wide 18”s. How important is it to drop the stance 1” ? My 91 has FX3. Are there any issues with the lowering kits and FX3?
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Old Apr 13, 2019 | 01:23 PM
  #23  
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Originally Posted by thomasfxlt
My instinct is to go with the wide 18”s. How important is it to drop the stance 1” ? My 91 has FX3. Are there any issues with the lowering kits and FX3?
Dropping the car's ride height is a separate decision: you can run any of the wheel/tire combos we discussed whether you lower the car or not. As for the FX3, I've never had that or messed with it, so I'm not 100% sure. However, my understanding is that the adjustability is just a valving change for damping rate, and that it isn't sensitive to position/displacement. That is, it doesn't have a ride height sensor of any kind - it just changes the damping rate to whatever you select. In that case, there should be no issues lowering the car 1". Do be sure to keep the stock bump stops on the car so that it doesn't bottom the shocks out and damage them.

FWIW, lowering the rear of a C4 is pretty simple: longer bolts for the ends of the springs. With any non-adjustable front leaf, lowering the front requires shaving the rubber pads at each end of the spring. This is doable, but removing that spring to do the mod requires more work.
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Old Apr 13, 2019 | 01:46 PM
  #24  
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Originally Posted by MatthewMiller
Dropping the car's ride height is a separate decision: you can run any of the wheel/tire combos we discussed whether you lower the car or not. As for the FX3, I've never had that or messed with it, so I'm not 100% sure. However, my understanding is that the adjustability is just a valving change for damping rate, and that it isn't sensitive to position/displacement. That is, it doesn't have a ride height sensor of any kind - it just changes the damping rate to whatever you select. In that case, there should be no issues lowering the car 1". Do be sure to keep the stock bump stops on the car so that it doesn't bottom the shocks out and damage them.

FWIW, lowering the rear of a C4 is pretty simple: longer bolts for the ends of the springs. With any non-adjustable front leaf, lowering the front requires shaving the rubber pads at each end of the spring. This is doable, but removing that spring to do the mod requires more work.
I’ll do the wheels and tires first then evaluate ride height. If that 1” drop will increase the “impact”, I’ll probably go for it.

I’m really hoping the brakes and calipers aren’t a horror show under the saw blades. I know a lot of people upgrade their brakes with 18’s but this is a 91’ touring convertible and I’m more interested in the curb appeal than track performance.

I think this car will look nice upgraded.

Last question... how much will the ride be impacted by 18’s (assume I go with a well-rated tire for ride quality).
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Old Apr 13, 2019 | 03:03 PM
  #25  
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Originally Posted by thomasfxlt
I’m really hoping the brakes and calipers aren’t a horror show under the saw blades. I know a lot of people upgrade their brakes with 18’s but this is a 91’ touring convertible and I’m more interested in the curb appeal than track performance.
Definitely don't waste time and money on a brake upgrade if you only street-drive the car. That whole trend is silliness for most people's usage. My car probably has twice the power yours does and I autocross it a lot, and I still use the stock J55 brakes. I just make sure it has very good fluid and pads that work better when hot. I have larger Wilwoods for the front that I would use for a track day event, but they don't allow the use of the stock sawblades, which I still use for street/wet/winter tires. Since I don't track the car right now, I don't use them. A 1" drop on your car will make a real difference in appearance.

Last question... how much will the ride be impacted by 18’s (assume I go with a well-rated tire for ride quality).
A little, but not much. Given the same tire model in both sizes, the 18 will be just a bit harsher. However, keep in mind that with the larger 18s you'll be able to run a bit less pressure for similar handling. So if you're running, say, 35psi now you could run the 18s at maybe 31-32psi and get back a fair amount of the ride quality. There's a bit of tunability in the ride quality using air pressures.
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Old Apr 13, 2019 | 07:22 PM
  #26  
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Originally Posted by MatthewMiller
Definitely don't waste time and money on a brake upgrade if you only street-drive the car. That whole trend is silliness for most people's usage. My car probably has twice the power yours does and I autocross it a lot, and I still use the stock J55 brakes. I just make sure it has very good fluid and pads that work better when hot. I have larger Wilwoods for the front that I would use for a track day event, but they don't allow the use of the stock sawblades, which I still use for street/wet/winter tires. Since I don't track the car right now, I don't use them. A 1" drop on your car will make a real difference in appearance.


A little, but not much. Given the same tire model in both sizes, the 18 will be just a bit harsher. However, keep in mind that with the larger 18s you'll be able to run a bit less pressure for similar handling. So if you're running, say, 35psi now you could run the 18s at maybe 31-32psi and get back a fair amount of the ride quality. There's a bit of tunability in the ride quality using air pressures.
Thanks for all the input!
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Old Apr 14, 2019 | 10:48 PM
  #27  
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Originally Posted by MatthewMiller
9" is the minimum recommended wheel width for a 275/40 tire (9-11"). That will work - not ideal for best track times, but it will be fine on the street. This offset will work nicely.


Same as above, and the tire size could be 275/35r18 on the wide end, or a 245/40r18 on the narrower end. The latter is probably a better overall fitment for this width tire.


You'd need 1/2" spacers to run these wheels, which is fine to use. You may need longer wheel studs to use them, though. For tires, either 285/35r18 or 295/35r18. I'd go with the 285s.


This is kind of an opinion-based, pro/con decision. To my mind, if you jump to 18s and pay for new tires, go with the wider 10.5" tires and spacers. They'll look better and give better performance. Your car will stand out from most C4s that have narrower rolling stock. People will compliment your car without exactly knowing why it looks badass compared to other C4s. I don't think you gain anything by going to the 18x9. If you're going to stick with 9" width wheels, then you might as well stick with the 17" wheels and use the tires you already own. That's money you can spend on other things.
Matt, why do so many of the 18 x 10.5 wheels say “rear only” for the vettes?
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Old Apr 14, 2019 | 11:03 PM
  #28  
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Originally Posted by thomasfxlt
Matt, why do so many of the 18 x 10.5 wheels say “rear only” for the vettes?
I don't know. I haven't seen that, but I haven't looked at OE-style repro wheels either. Maybe they are referring to the fact that this size only came on the rear of C5 Z06s?
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