Wheel and tyre weights

[Alex Jenner <alexj@domain.elided>]

Peter Webb wrote:
> Check the numbers:
> 
> My car stock: (phonedial weight from memory and probably a generous
> approximation).
> 
> S-03 Pole Position - 22lbs  205/50-15 + ~23lbs Milano Phonedial wheels =
> 45lbs unsprung.

> S-03 Pole Position - 25lbs  225/45-17 + 17lbs Team Dynamics DTM wheel =
> 42lbs unsprung.

In order not to waste too much digest space, I won't repeat all the
numbers again, but I think a better summary might be "expensive wheels
and tyres can often be lighter than original equipment".

Phonedial wheels are heavy. In this example your 17" tyres are heavier
than the ones with the higher sidewalls.... despite your statement in
the same digest "Logically, it's less rubber" (possibly the increase is
due to the extra width?). But your larger wheels save 6lbs, which is
good, but the reduced weight didn't come from the increased size, did
it?

I'm sure if Team Dynamics make a "DTM" wheel in 15x6, it will weigh even
less than 17lbs. Now match those up with your original tyres and you get
a total of 39lbs.

If your original wheels were the 6.5 X 14 Montreal Turbinas (12.8lbs),
then you'll be able to match that with a light tyre for an even lower
figure.

In general, I think you will find that 2 rubber rings (1 inch high) that
make up the change in sidewall height, aren't going to weigh as much as
2 inches extra alloy rim diameter.

Someone else gave examples of Ferrari's with 17-19" wheels as examples
of the advantages of big wheels.... but these are big heavy cars. If we
take these as examples of the correct ratio of wheels size / total
weight, then I would expect a Spider should be running something around
14-16".

Best Regards
Lex Jenner

Auckland/New Zealand
2 x Alfasuds (13" wheels)
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