wheel weight figures (unsprung details)

redzed · 10-12-13, 09:46 AM

Right might be a tad race geeky and not interesting but it below is the weight per wheel of mk1/2 and aftermarket rims and the effects it has on your car.

Weight of one wheel and tyre:

Mk2 rim 20.4kgs
mk1 rim 18.3kgs
MK1 rim on slicks 18.1kgs
Rota boost lightweight wheel 17.3kgs

Unsprung mass is the weight in a car not held up by suspension; so wheels tyres brakes etc. The larger the wheel diameter and heavier takes a lot more force to turn quickly and hence slows the car. Rule of thumb is for every 1kg removed from wheels/tyre weight is the same as removing 10kgs from the car it also impacts the suspension less as the weight of the wheel is in effect hitting the suspension at high speeds so lighter wheels also helps ride quality. This only affects the driven wheels i.e front on a zs, rear on a m3 etc. 9ive heard maany people say its for all but i dont see logically how as they are being pulled pushed not physically spun round my the engine. So running a zs on aftermarket wheels is the same as removing up to 60kgs from the car, the less weight the less energy required actually helps in small amounts to save fuel (marginally) and does improve acceleration. One for the racing guys here and the speed/fuel conscious.

On this note if anyone else has a boring morning in their workshop at any time with a set of scales and some 16inch hairpins or other lightweight wheels can you post them on this thread?

petet16 · 10-12-13, 11:34 AM

It's a shame that mk2 11 spokes are so darn heavy.

I wonder what 17x7.5 Kei F10's weigh.

Mark S · 10-12-13, 01:26 PM

I think it may be nearer 1 to 4, but either way, its multiplied.

Tyres make a huge weight difference, best to have wheel only weights.

Whilst the mk2 rim is heavy, its only average compared to most after-market rims. around 9.5-10kg from memory.

Rota are light, very thin and prone to break, the subzero is the lightest cast they do.

7j rims opens many more options.

ultimately, a forged, mag or spun alloy will save a lot of weight, combined with a lightweight tyre - tyres can vary so much.

10kg for a wheel and tyre combo is poss.

rotational inertia, unsprung weight etc is key, certainly for the circuit, again, this is key to the type of dampers you may choose for a race car.

Mark S · 10-12-13, 01:26 PM

Quote:

Originally Posted by petet16

It's a shame that mk2 11 spokes are so darn heavy.

I wonder what 17x7.5 Kei F10's weigh.

as much if not more than mk2's

Jay-ZS+ · 10-12-13, 01:49 PM

I wished I'd gone for carbon wheels, had a guy from a company that produced them present to us the product and the manufacturing process. Would have been the best part of a grand and would have most likely had to go with single stud. Would have been nice though!!

talkingcars · 10-12-13, 06:12 PM

Quote:

Originally Posted by Mark S

Tyres make a huge weight difference, best to have wheel only weights.

Quote:

Originally Posted by Mark S

combined with a lightweight tyre - tyres can vary so much.

contradict yourself there Mark!

The tyres make up part of the unsrung weight so should be included.

Mark S · 10-12-13, 06:39 PM

Quote:

Originally Posted by talkingcars

Tyres make a huge weight difference, best to have wheel only weights.

Quote:
Originally Posted by Mark S View Post
combined with a lightweight tyre - tyres can vary so much.
contradict yourself there Mark!

The tyres make up part of the unsprung weight so should be included.contradict yourself there Mark!

The tyres make up part of the unsprung weight so should be included.

I meant when measuring wheel weights, yes the combined weight is unsprung, without a doubt, but if your looking for a lightweight wheel, would you ask how much it weighs with tyres on? or without? - that was the point in that comment.

Quadcam24 · 10-12-13, 08:30 PM

correct, tyres vary as much in weight as wheels.
i found a list of tyre weights on the net some years ago and you can make big savings going for the right one, of course no point going for megalight tyre if the grip is poor, so its all a compromise.

redzed · 10-12-13, 10:33 PM

Quote:

Originally Posted by Mark S

I meant when measuring wheel weights, yes the combined weight is unsprung, without a doubt, but if your looking for a lightweight wheel, would you ask how much it weighs with tyres on? or without? - that was the point in that comment.

comment understood, and a valid one. thats why i put in the mk1 rim with normal tyre and a racing slick so you see a difference there.

redzed · 10-12-13, 10:35 PM

Quote:

Originally Posted by petet16

It's a shame that mk2 11 spokes are so darn heavy.

I wonder what 17x7.5 Kei F10's weigh.

ive got a set of 18s dont know the brand which weigh the same as the mk2s so dont think theyre heavy as wheels go. Picked up a bmw wheels from an m3 today after this and it must have been 26kgs at least, bloody heavy thing!