Light wheels / rims ain't always the best when racing

[Guni]

I had someone tell me recently that even at 17.5KG per wheel (Rims + Tyre + Air) that it is still too "heavy". So the question is, when is it ever "light enough" ??? Rims are about 6 - 10KG depending on size so the rest is made up by tyres and air ......

I felt that the weight was ideal as once the car is rolling, it shouldn't matter how much the wheel weighs as we all know, acceleration consumes the most power. Once you are cruising, don't think the weight of the wheel matters. The air in it however, does! B)

Your 4 wheels is meant to keep you and the car on the ground anyways. Your not a piloting a space shuttle pulling away from earth's gravity which means you do not need your wheels to be anorexic. But each to their own ;)

Which comes to the article below ...... which will upset most but oh well, time to wake up and smell the 5h!ts ...

The article is about testing two different set of wheels using same car setup and tires. They were trying to see how lightweight versions of the wheel would compare to a more rigid one.

Enjoy

http://og-made.com/archives/1904

[Guni]

The link above also shows how bigger wheels might not necessarily be the best for safety wise as the lower profile tires deform around corners.

[and1]

Design of the wheel plays a factor in strength and rigidity. Also the material used and the way the wheel is manufactured. Ah materials engineering how I love you lol.

Best alternative is to find a wheel in a smaller size as that saves more weight than going lightweight of the same size wheel. Chunky tyres ftw!!

[dwee.]

Is this why you're going back to stockies/16's?! :P

[and1]

Is this why you're going back to stockies/16's?! :P

Who me?

I've never had any rims besides the stockies on my car..

[dwee.]

Who me?

I've never had any rims besides the stockies on my car..

Nah, I meant Guan. I know he's been wanting to go back to 16's for a while..

Interesting read though, and video too!

[SuperDave]

I had someone tell me recently that even at 17.5KG per wheel (Rims + Tyre + Air) that it is still too "heavy". So the question is, when is it ever "light enough" ??? Rims are about 6 - 10KG depending on size so the rest is made up by tyres and air ......

I felt that the weight was ideal as once the car is rolling, it shouldn't matter how much the wheel weighs as we all know, acceleration consumes the most power. Once you are cruising, don't think the weight of the wheel matters. The air in it however, does! B)

Your 4 wheels is meant to keep you and the car on the ground anyways. Your not a piloting a space shuttle pulling away from earth's gravity which means you do not need your wheels to be anorexic. But each to their own ;)

17.5kg with a tyre on a 15" to 17" rim is fine, I wouldn't say it's heavy at all. Tyres are heavy buggers, and semi slicks are heavier than road tyres.

Newton's first law of motion disagrees. When you hit a bump the wheel needs to move upwards (or droop depending on the bump/jump), along with the rest of the suspension. This is referred to as unsprung weight. The heavier it is the more it wants to maintain it's current status (stationary) than if it was lighter. More unsprung mass reacts slower to the bump.

In your cruising example the rotating mass is still under Newton's laws of motion. There is an outside force caused by the friction of the tyre on the road, wind resistance/drag and other drivetrain frictions. All these are conspiring to slow the car down. The heavier wheel will still need more energy input to maintain a cruising speed than a lighter wheel.

But in short, it's cheaper if people lost 10kg of weight around their belly (majority of Asian's excluded :P) than spend $3000 getting the lightest rims possible. That said F1 rims weight next to bloody nothing, it's all about design.

[Hiro]

In your cruising example the rotating mass is still under Newton's laws of motion. There is an outside force caused by the friction of the tyre on the road, wind resistance/drag and other drivetrain frictions. All these are conspiring to slow the car down. The heavier wheel will still need more energy input to maintain a cruising speed than a lighter wheel.

But at the same time, a heavier wheel will act as a flywheel, storing inertia and being more resistant to speed changes (either faster or slower) than a light wheel.

[Guni]

Hmmmmm .....

[Blind Kid Seeks]

+1 Superdave...

Unsprung weight is king! evry kg you can lose from your unsprung weight is the equivelint to 8 KGS from the weight off your car.... if i remember correctly

Unsprung Weight V's Sprung Weight

[prometheus]

This reminds me of a segment on the Australian version of Top Gear where they raced a Commodore V8 of some description (forget which specific model) around the track on low profile tyres and a set of higher profile tyres.

With the higher profile tyres, the car handled better and got a faster time around the track.

[SuperDave]

^ exactly. Many people with no motorsport experience believe that low profile tyres provide more grip; they just confuse it with sidewall flexing thinking less is better. The sidewall forms part of the suspension system of the vehicle and not to forget there is a certain slip angle the tyre needs to produce it's maximum level of grip, a low profile tyre makes it harder to reach and maintain that slip angle. There is obviously a point at which the sidewall becomes too large, just like it can become too small.

[Hiro]

This reminds me of a segment on the Australian version of Top Gear where they raced a Commodore V8 of some description (forget which specific model) around the track on low profile tyres and a set of higher profile tyres.

With the higher profile tyres, the car handled better and got a faster time around the track.

It was more than just the tyres though, it was wheel-size too. The test car was a Walky wagon, and they were comparing the stock wheels to the option package (something like 19" to 20"), with overall diameter still the same.