Contour Enthusiasts Group Archives Forums Modifications General Mods Unsprung Weight & Performance

Ok, so as we have a limited number of wheels to choose from (4 x 108, what were they thinking?), I am constantly bummed out by the weights and styles available. Even if I find a style I like, it?s usually heavy. The OZ SuperT and BBS RX, light, good looking, strong, are no longer available for our cars. I have found a wheel I like, but it comparatively heavy. What performance difference can I expect using a 17Lb. Vs. a 22Lb. Wheel? Assume 17? and 225/45-17.

Is there a formula that I can apply, or perhaps some on-line conversion calculator?

Superleggeras are nice, but rumor has it there will be several pair at SZ02 so I am looking elsewhere. SSRs don?t work for me aesthetically and the 10 pairs of Volks in this country, at $550 each, are out of my budget???..

Mark - needs new wheels. Yes it?s a NEED; it?s a psychological thing.

Hey Mark... Take a look at Sport Compact Car mag. They had an article in performance dictionary I think all about unsprung weight and a TON of equations you can use. I can't find my issue with it though..

Ray

You want, light, good looking, cheap-ish rims that no one else has? Gee whiz, you're not too demanding, are ya bottle man?

When you guys think about that, do you factor in the tires?? Saving 2 lbs on a wheel isn't gonna help much if you gain it back on the tires. I've never weighed different brands of tires side by side but I think there might be differences... I've always weighed my rolling stock with tires mounted.

FWIW, my E0 SVT wheels with Goodyear GT+4s weighed 40lbs each. My 18" Ace Spades with Toyo T1-S also weigh exactly 40lbs. They do slow the car down some because those 40 lbs are concentrated farther to the outside than on the SVT 16" setup. As far as the suspension is concerned though, the weight of the setup is the same...

HTH,

Most tires of the same type are very close in weight when new. Probably within 1 or 2 lbs or so. Just figure on around 20-22 lbs per tire, unless you're into race tires, in which case the Hoosiers seem to be the lightest. I would choose tires based on intended use, and performance, with weight only a minor issue unless somebody is really outside the norm.

Check out this Miata tire weight database The sizes in the table run small for us, but good for relative comparison. Also has links to Bridgstone, Dunlop, and Firestone websites that catalog weight for every tire and size they sell. Also has links to at least two other wheel weight databases, including the best I've seen to date.

In my estimation, you will "gain it back in the tires" no matter what you do. Shave weight where you can. Drive off the rest.

BTW, my RE 930s are about 6 lbs lighter after 30k.

keep in mind, IIRC (don't quote me, because my memory may be fuzzy ) that every pound of unsprung weight is roughly equal to seven pounds of sprung weight.

22-17=5 lbs PER wheel X 4 = 20 lbs unsprung weight

That's worth ~140 lbs of sprung weight!!!

No wonder lightweight wheels are so important!

Pity thats not thought of when selecting spring rates!!!.The only way is to set the car up on scales at each wheel.........