Just wondering if anyone knows was affect putting on heavier rims/tires will have on acceleration? Anyone done any back to back tests with large vs small rims.

When I weighed my aftermarket 18" rims and 255 tires, there were around 6 pounds more each then the stock rims and tires. Just worried I am loosing some performance because of this.

Thanks

 

In the old days light weight wheels and tires made for a 1/10 reduction in et. Goodyear front runners and a 15" aluma star rim combo weigh in at 20 pounds. A GT spare tire and rim weigh 30 pounds. So a stock tire and rim will be even more. I am not saying that a 15" rim will fit however. Just a note on the lighter mass will help reduce et.

 

In the old days light weight wheels and tires made for a 1/10 reduction in et. Goodyear front runners and a 15" aluma star rim combo weigh in at 20 pounds. A GT spare tire and rim weigh 30 pounds. So a stock tire and rim will be even more. I am not saying that a 15" rim will fit however. Just a note on the lighter mass will help reduce et.
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I've heard 10lbs unsprung weight is .1 et on the 1/4 mile. Add 10lbs of tires slowdown 1/10.

 

Yeah anything you lose is only good. Its the whole unsprung weight thing - remember its not just the fact that the wheels are heavier and adding weight to the car overall, the car has to work harder to spin them too.

 

I believe 100 lbs = a 1/10th.

 

And I just reread you post - 6 pounds EACH???

Ouch....

 

There was some import crap magazine that did a test. They switched from 17's to 15's and picked up 2 tenths in the quarter. Of course thats a 150 horse import but funny none the less.

 

Ya 6 pounds each. At the time, the stock 17" rims had 225 snow tires on them and the 18" rims have 255 Nittos. Not sure if the tire or the rim is accounting for most of the 6 pounds.

 

I would love to go to 15" wheels. That would, for me, require going to a 9" rear. For me, if I'm going to change anything on the rear, I would have to go 100% and make the rear sturdy. Going to a 9" rear would add more weight, but I would be able to get true slicks on there. True slicks only go upto 15".

 

my stock GT ran 2/10's faster then a GT at the same track with a chip and exhaust, the only thing we could figure out is that he had 20's

 

Thats for regular weight not unsprung weight, like someone else said unspung weight takes alot more hp cause the car has to work harder to move parts rather then just move weight

 

Here's a tidbit I found on this. I'm learning something new everyday!

http://victorylibrary.com/mopar/sprung-c.htm

 

Not to argue with the site, but I've read a lot of stuff that disagrees with this. A magazine swapped brakes and the car slowed down. The larger brakes weighted alittle more, not 100lbs. They said the larger rotor put the weight further away from the axle, making to harder to turn the wheels. I'm not a science major, please forgive the explaination. At another site, a guy swapped rear tires and lost 3.5 rwhp. I think he went from 265s to 315s. I understand weight is weight, but when you're spinning that weight it has a dramatic effect on performance.

PS
At FRPP, 18" wheels weighted about 5lbs more than 17" wheels. Chrome added 2lbs per wheel.

 

Ya 6 pounds each. At the time, the stock 17" rims had 225 snow tires on them and the 18" rims have 255 Nittos. Not sure if the tire or the rim is accounting for most of the 6 pounds.
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I bet the tires are at least 1/2 that gained weight, not that it matters.

 

IMO, the article is confusing and I wonder what the motivation was for writing it.
I will take lighter weight wheels/tires ten days out of ten. Whether there is a standard way to measure benefit or not.

 

The new Saleen's (w/o supercharger) has 20" wheels and is slower than a stock GT. So, even with it's slight boost in HP & TQ over the stock GT, you have to wonder. I plan to go to 18x9 wheels and 255/45/18 tires, but I am not really worried about straight line performance loss, just better traction and handling over stock. This size will keep the same rolling diameter as the stock tires and wheels.

 

I have to wonder if Saleen's 20" wheels are about bling more than handling. I read somewhere there isn't a handling benefit after 18" wheels. Weight offsets the advantages.

 

Fantastic! Finally a wheel thread that is about PURE TECH!!!

(grin)


Increasing the weight of your wheels results in multiple phenomena.


1) More overall weight to accelerate in a straight line (small but significant)
2) More weight to spin up to speed (significant)
3) More unsprung weight (wheels, tires, and some suspension components), which affects your suspension dynamics (possibly hurting roadholding and handling more than it helps!)

If you go to a TALLER wheel/tire, it usually means more weight as well (see all 3 above). But let's say you buy an ultra-light 18 to replace your heavy 17's, and the weight stays flat. If the mass moves more to the outside (taller tire and wheel), then more rotational inertia, i.e. more energy to spin up. AND there is a gyroscopic affect (caused by the rotational inertia) that will affect vehicle turn-in.

Luckily most of us will attempt to keep an overall same height, so this effect is offset somewhat.... but your 19" wheel with a wide tire is definitely going to absorb power and slow your braking.

Why the heck do you guys think that drag cars run skinnies up front?

 

The wheels I have on order right now are 20.5 lbs. each, vs 27 lbs. for the stock bullits. They will remain a 17" diameter. As far as modding for performance, I think a lot of people should look for function and then looks, instead of the other way around. Most of the functional wheels of the past later became popular and their "look" became the standard.
Paul