Light weight wheels and tires?
Thread Starter
Instructor
Joined: May 2010
Posts: 230
Likes: 2
From: indianapolis Indiana
Light weight wheels and tires?
I have ultra light weight wheels and tires on my c5. I have noticed that car feels lot lighter now. My concerns are
1. does it interfere with handling of the car? My c5 used to feel more stable at highway speed with stock wheels and tires.
2. Is it safe to drive with light weight wheels on highway. Under moderate acceleration or downshifting feels very unstable. It feels like car is going to go sideways.
Any suggestions?
1. does it interfere with handling of the car? My c5 used to feel more stable at highway speed with stock wheels and tires.
2. Is it safe to drive with light weight wheels on highway. Under moderate acceleration or downshifting feels very unstable. It feels like car is going to go sideways.
Any suggestions?
Tech Contributor
Joined: Jan 2007
Posts: 19,448
Likes: 1,155
From: Dyer, IN
I have ultra light weight wheels and tires on my c5. I have noticed that car feels lot lighter now. My concerns are
1. does it interfere with handling of the car? My c5 used to feel more stable at highway speed with stock wheels and tires.
2. Is it safe to drive with light weight wheels on highway. Under moderate acceleration or downshifting feels very unstable. It feels like car is going to go sideways.
Any suggestions?
1. does it interfere with handling of the car? My c5 used to feel more stable at highway speed with stock wheels and tires.
2. Is it safe to drive with light weight wheels on highway. Under moderate acceleration or downshifting feels very unstable. It feels like car is going to go sideways.
Any suggestions?
Thread Starter
Instructor
Joined: May 2010
Posts: 230
Likes: 2
From: indianapolis Indiana
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
If you moved from stock wheels (which are already just about the lightest wheels you can get) to these then the weight difference should be minimal. Certainly not enough for a perceived difference on your part I wouldn't think... If you were to list the symptoms without saying that you'd just put new wheels on I'd be thinking you had a damaged or improperly sized sway bar in the rear. A lot of people on this forum have "upgraded" to C6Z06 rear sways while running stock or near stock width rear tires... You didn't by any chance upgrade your suspension components along with the wheels did you?What are the wheel specs? Diameter, Width, Offset, Bolt Pattern, Weight. Are you running spacers or adapters? Which tires did you go with and what size?
Last edited by cdkcorvette7; Dec 19, 2011 at 01:35 AM.
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
You definetely need to look elsewhere in your suspension. Unsprung weight affects your ride and handling (the wheels and tires) and lighter is better, not worse. It would have to be substantially lighter for you to actually feel the difference that much, even in a positive way.
Tech Contributor
Joined: Jan 2007
Posts: 19,448
Likes: 1,155
From: Dyer, IN
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
You definetely need to look elsewhere in your suspension. Unsprung weight affects your ride and handling (the wheels and tires) and lighter is better, not worse. It would have to be substantially lighter for you to actually feel the difference that much, even in a positive way.
now what is the wt difference. and what is the wheel size?
Thread Starter
Instructor
Joined: May 2010
Posts: 230
Likes: 2
From: indianapolis Indiana
If you moved from stock wheels (which are already just about the lightest wheels you can get) to these then the weight difference should be minimal. Certainly not enough for a perceived difference on your part I wouldn't think... If you were to list the symptoms without saying that you'd just put new wheels on I'd be thinking you had a damaged or improperly sized sway bar in the rear. A lot of people on this forum have "upgraded" to C6Z06 rear sways while running stock or near stock width rear tires... You didn't by any chance upgrade your suspension components along with the wheels did you?I bought the car used. I went under the car and everything looks stock.
What are the wheel specs? Diameter, Width, Offset, Bolt Pattern, Weight. Are you running spacers or adapters? Which tires did you go with and what size?
You definetely need to look elsewhere in your suspension. Unsprung weight affects your ride and handling (the wheels and tires) and lighter is better, not worse. It would have to be substantially lighter for you to actually feel the difference that much, even in a positive way.
Weight difference is perceivable. I havnt weighted them but i would say stock wheel weigh as much as combination of new wheel and tire
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
wheels size is 245/30/20 in front and 285/30/20 in rear. Tires are falken. No spacer or adapter.
Car hasnt gone side ways or anything yet. I get "traction control" warning when down shifting on highway or even at stop light under moderate acceleration
Weight difference is perceivable. I havnt weighted them but i would say stock wheel weigh as much as combination of new wheel and tire
Car hasnt gone side ways or anything yet. I get "traction control" warning when down shifting on highway or even at stop light under moderate acceleration
Weight difference is perceivable. I havnt weighted them but i would say stock wheel weigh as much as combination of new wheel and tire
Le Mans Master
Joined: Dec 2008
Posts: 5,414
Likes: 25
From: Texas
Sounds like the delta between your front and rear tires might not be big enough. Your rear tires need to be a bout an inch taller than your fronts or your AH/TCS will play hell with you. I'm on my phone and don't have access to a calculator so someone else will need to check that...
OD of the tires needs to be larger in the rear compared to the front....
Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
Car hasnt gone side ways or anything yet. I get "traction control" warning when down shifting on highway or even at stop light under moderate acceleration
With a 285/30/20 you have no sidewall to speak of so there is no give during acceleration or deceleration.
With a 285/30/20 you have no sidewall to speak of so there is no give during acceleration or deceleration.
Burning Brakes
Joined: May 2007
Posts: 829
Likes: 0
From: San Francisco CA
I think that's probably it, the tires are so low profile and don't give so they just bounce the suspension around and also have less grip over all so it seems like the car is unstable.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
You should inspect the suspension for bad parts and then get the car aligned.
I would bet money your new combo do not weight less than the stock rims alone. The stock C5 wagon wheels are <30lbs each and the other stock C5 wheels are <20lbs each. Your new rubber will weight something like 26F and 30R. So, your new rubber alone will weight similar to the wagon wheels or more than any other stock C5 wheel. I would also expect your new rims to weight 20-25lbs each.
I would expect 20's to have more inertia than the stock sizes, which will negatively affect acceleration and braking, even if they do weigh 4 or 5 lbs less per wheel compared to the stock combo. You're moving more weight to the outside of the wheel and inertia is the mass times the radius squared. If mass goes down 10% but the radius of the mass goes up 10% then the inertia goes up 10%.
Finally, if you have really lowered the car (more than about 3/4") then your shocks are pretty much bottomed out and these new wheels have less give meaning the car will bounce around more going over bumps.
Peter
I would bet money your new combo do not weight less than the stock rims alone. The stock C5 wagon wheels are <30lbs each and the other stock C5 wheels are <20lbs each. Your new rubber will weight something like 26F and 30R. So, your new rubber alone will weight similar to the wagon wheels or more than any other stock C5 wheel. I would also expect your new rims to weight 20-25lbs each.
I would expect 20's to have more inertia than the stock sizes, which will negatively affect acceleration and braking, even if they do weigh 4 or 5 lbs less per wheel compared to the stock combo. You're moving more weight to the outside of the wheel and inertia is the mass times the radius squared. If mass goes down 10% but the radius of the mass goes up 10% then the inertia goes up 10%.
Finally, if you have really lowered the car (more than about 3/4") then your shocks are pretty much bottomed out and these new wheels have less give meaning the car will bounce around more going over bumps.
Peter
Thread Starter
Instructor
Joined: May 2010
Posts: 230
Likes: 2
From: indianapolis Indiana
You should inspect the suspension for bad parts and then get the car aligned.
I would bet money your new combo do not weight less than the stock rims alone. The stock C5 wagon wheels are <30lbs each and the other stock C5 wheels are <20lbs each. Your new rubber will weight something like 26F and 30R. So, your new rubber alone will weight similar to the wagon wheels or more than any other stock C5 wheel. I would also expect your new rims to weight 20-25lbs each.
I would expect 20's to have more inertia than the stock sizes, which will negatively affect acceleration and braking, even if they do weigh 4 or 5 lbs less per wheel compared to the stock combo. You're moving more weight to the outside of the wheel and inertia is the mass times the radius squared. If mass goes down 10% but the radius of the mass goes up 10% then the inertia goes up 10%.
Finally, if you have really lowered the car (more than about 3/4") then your shocks are pretty much bottomed out and these new wheels have less give meaning the car will bounce around more going over bumps.
Peter
I would bet money your new combo do not weight less than the stock rims alone. The stock C5 wagon wheels are <30lbs each and the other stock C5 wheels are <20lbs each. Your new rubber will weight something like 26F and 30R. So, your new rubber alone will weight similar to the wagon wheels or more than any other stock C5 wheel. I would also expect your new rims to weight 20-25lbs each.
I would expect 20's to have more inertia than the stock sizes, which will negatively affect acceleration and braking, even if they do weigh 4 or 5 lbs less per wheel compared to the stock combo. You're moving more weight to the outside of the wheel and inertia is the mass times the radius squared. If mass goes down 10% but the radius of the mass goes up 10% then the inertia goes up 10%.
Finally, if you have really lowered the car (more than about 3/4") then your shocks are pretty much bottomed out and these new wheels have less give meaning the car will bounce around more going over bumps.
Peter
front tires and rear tires do have 1 inch difference in diameter difference.
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
I would say that the negative sensations you are feeling are a result of running 20" wheels front and rear. That's considerably larger than your stock rim diameters. You probably have almost no sidewalls. Plus, I doubt a rim that big can be lighter than your stock wheels. More likely they actually weigh more, that would make the car ride worse. You should weigh your tire/wheel combos, both the stock and custom sets.
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
I would say that the negative sensations you are feeling are a result of running 20" wheels front and rear. That's considerably larger than your stock rim diameters. You probably have almost no sidewalls. Plus, I doubt a rim that big can be lighter than your stock wheels. More likely they actually weigh more, that would make the car ride worse. You should weigh your tire/wheel combos, both the stock and custom sets.
You'd have to pay a fortune to get forged wheels in that size that are lighter than stock. Based upon what I saw here in this forum, my 17" front wheels weigh only about 16 lbs.
