Alloy wheel 'performance factor' ?

[nissangeek]

We all know the lighter any part of a car the better. Hence alloys tend to be lighter. But the further any mass of the alloys is to the outside of the wheel, the further it travels and hence the more wokr has to be done to overcome this resistance.

So 2 things affect the 'performance' of any wheel - overall weight and 'weight profile' from centre of wheel to edge. Does anyone know of any factors used to quantify these differences when comparing alloy wheels ?? Also, is there a method to combine them to give an overall performance factor ?

A consequence of this is something many ppl probably have not thought of - that a smaller alloy (with some inherent disadvantages like tire flex when cornering for instance) may have a significant (relatively speaking) performance benefit to larger alloys. It is possible that larger, lighter wheels could be worse overall than smaller wheels which are heavier.
Of course a larger wheel will tend to have more 'alloy wheel' as opposed to tire and metal is heavier than tire.

[A13_SXT]

geek

i have no idea what your talking about, i bought my wheels because they looked good

[fergS13]

ha thats the best thing ive ever read

[nissangeek]

Did i put this in the wrong section ?

[fergS13]

i would go with yes swiftly followed by possibly accompanied by i dont know

[nissangeek]

Is the question/concern far too 'geeky' ?

[fergS13]

oh yes its full of geeky goodness lol its actuall quite intreguing

[CNHSS1]

most race cars run smaller wheels than 'street' cars. Many racers use 13" wheels as slicks are much much lighter due to having little or no steel banding in them, which makes the wheel the heavy bit in the equation. Slick side walls are also much stiffer than the equiv road tyre, so they dont need to be ultra low profile like a road tyre to gain sidewall stiffness. In order to keep the wheel weight down, most race wheels of 13"-15" are split rims with cast or billet centres for strength and spun ally rims to keep the wheel low and the inertia. Think of wheels like an engines flywheel, weight further out towards the edge has a more detrimental effect than close to the hub centres.

as an example when moving from Kumho V700 semi-slicks (like R888s or Yoko A032R/Ao48Rs) which are all road car carcass based to Avon slicks, 1 x Kumho in 225/50-15 weighd the same as 2 x 10" wide Avon slicks!!.

The split rims i use (Image Billets and Compomotive cast centres) weigh about 60% of a regular lightweight cast wheel

[Actual_Ben_Taylor]

I choose wheels that A- fit over my brakes and B- are light.

[nissangeek]

Of course brakes can affect wheel choice.

[CamInHead]

I think you're being pedantic over minor details tbh.

[John Bennett]

I've never known anyone actively choosing wheels for a road car based on inertia, especially as you need the appropriate tyre aswell to know the value.
People are subconsciously accounting for it already in choosing light wheels and rarely opting for 19 inch+ enormous rims (and other than that, I'd be suprised if it makes much difference from wheel to wheel).

[croustibat]

if you are looking for every split second you can on a track, then get light wheels. They will cost you an arm and a leg, and will break on any impact. but will give better acceleration and braking. The problem is also that when you suppress inertia, it will be easier to block or spin a wheel. The inertia lets you "smooth" these. Same as a flywheel, really.

if you are not looking to shave times on your race car, get cheap wheels without funny design, they will only weight a little more, but you can buy 4 for the price of 1 volk te28 or te37

and of course, get wheels that fit your brakes. I'd say dont get 18" on an S13, there is not enough sidewall left (if you feel like keeping standard wheel + tyre diameter) . 17" is the best imho.

[nissangeek]

I'm not about to buy ant lightweight wheel - I was just interested in the inertia factor. Funny how people make assumptions and run with the ball !

[sxbaz]

well if ur not buying them and nobody else really cares, whats the point of this thread?

[bobbitt]

a good laugh!

[s13 paul]

small wheels give you quicker acceleration throuh the gears but lower the top speed where large wheels increace the top speed but can make getting there slower. depends on where and what you are using the car for. street use you wont notice the differance but on a track can make a massive differance

[Django67]

Basically all you need is a set of R32GTR wheels.

[nissangeek]

where large wheels increace the top speed

I beg to differ How can large (by this you mean heavier right) wheels increase top speed ?

[sxbaz]

I beg to differ How can large (by this you mean heavier right) wheels increase top speed ?

large doesnt always mean heavier, thats like saying a baloon is larger than a brick so it must be heavier