weight of wheels and tires

[The DON]

I know the lighter the wheels and tires, the better the car handles, but how significant is it? Will I actually feel the difference with lighter wheels and tires? Will I be able to turn up better lap times?

Some time ago, somebody told me that every pound I save on the wheel + tire, it equals to saving 12 pounds on the car, true?

In search of the light....

The Don

 

[nsxtasy]

Originally posted by The DON:
Will I actually feel the difference with lighter wheels and tires? Will I be able to turn up better lap times?

Not likely, except perhaps due to the placebo effect.

Originally posted by The DON:
Some time ago, somebody told me that every pound I save on the wheel + tire, it equals to saving 12 pounds on the car, true?

There is an equivalency because wheels and tires are unsprung weight (not suspended on the car's suspension), but it's not that high; I've more typically heard ~4 pounds, not 12.

[This message has been edited by nsxtasy (edited 22 November 2002).]

 

[sjs]

Originally posted by nsxtasy:
There is an equivalency because wheels and tires are unsprung weight (not suspended on the car's suspension), but it's not that high; I've more typically heard ~4 pounds, not 12.

... in terms of handling. Then there is the rotational mass aspect.

You didn't say what wheels you have. If they are stock then they are already fairly light and I'd agree with nsxtasy. On the other hand, if they are boat anchors (as most flashy aftermarket wheels tend to be) then you will get a more noticeable improvement.

 

[1BADNSX]

I've done the calculations for the rotational mass effect on NSX acceleration. The wheels are 1.5 times their mass in effect on acceleration. The tires are 2 times.

No where near 12 times. The effect of unsprung mass will depend on your springs and shocks and how well they are setup, but for most NSX's this will be a small effect.

Bob

 

[docjohn]

To answer the subjective part,If you compare stock to other wheels no real diff as has been said but when I switch from the blitz-3 wheel to the ssr-c then yes I do feel the difference the car feels livelier and does everything more crisply.The diff in wheel/tire weight in this ex. is ~15lb/corner!

 

[nsxtasy]

Originally posted by docjohn:
The diff in wheel/tire weight in this ex. is ~15lb/corner!

The difference in weight of the wheel/tire combination was 15 POUNDS???

Gee, that sounds like an awful lot... I thought 5 pounds was a big difference.

 

[sjs]

As best I can recall, most "common" wheels I've checked are at least 10 lbs heavier that stock. Like I said, boat anchors. So even using the calcs mentioned above, times four corners, it's bad, not to mention the handling aspect and the extra beating your suspension takes.

 

[blurr]

It isn't just the Wheels. Tires have a larger effect than the wheels because the weight of farther out.

I changed from 245/40/17 pilot Sports to 245/45/17 Azenis in the rear and the weight went up 8lbs per side. The fronts stayed the same size as stock and went up 3 pounds per side. The difference in the front being tire brand and corded vs new.



[This message has been edited by blurr (edited 22 November 2002).]

 

[Lud]

Even if the wheel weight stayed the same, big street tires weigh a LOT.

Tire weights also vary by brand/model of tires. There is easily a 5lb or MORE variation between different brands and models of the same size performance tire in the sizes commonly used on the NSX. I would not be at all surprised if you could find larger variations between brands for the wider 18 and 19 inch tires.

And of course some tires like Hoosier slicks are extremely light, but not really streetable.

[This message has been edited by Lud (edited 22 November 2002).]

 

[Chuck]

When I recently unmounted my Kumho Ecsta V700 285/30 18 (track and street tire) and replaced them with the Michelin MMX3 (285/35 18 street tire)I found the Kumho's weighed 23 lbs each and the Michelin's weighed 31 lbs each.

 

[sjs]

Many manufacturers list weight in their tire specs online. And yes, they too are a big variable especially as they are at the extreme outer circumference. But at least there is also some potential benefit from selecting a heavier tire if it otherwise contributes more performance than it detracts.