900 wheel size question

I (think I) got 16 wheels right now. What is the benefit of getting 17 or 18 wheels. ( '88 900i 8v) thanks, tom

Reply to
tom
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Only cosmetic benefits, but your teeth will fall out. Stick to your

16 wheels.
Reply to
Johannes H Andersen

Well not really theres many benefits other than cosmetics. The main one that would apply in a road car is that the height of the sidewall is reduced proportionaly to the size of the wheel, the smaller the sidewall the less sidewall flex will occur meaning sharper handling and an increased ability to make it stick during high G/high speed cornering.

Following on from this under hard braking from speed (think really hard braking) the 'stiffer' sidewalled thinner (in a radial sense) tyre won't pool as much as the weight shifts onto the fronts meaning that you able to brake and steer at the same time more effectively and eliminiate/reduce the risk of pulling a tyre off the rim if it goes pete tonge.

A large rolling radius, which can be produced by enlarging the size of the wheel will also directly impact the final gearing of the car, meaning in the very simplest terms you can gain top end or increase acceleration by varying the size of the wheel/tyre combination.

Going a stage further many wheels designed for race use are made not of Alluminium alloy but of a Magnesium alloy, they are incredably light, lighter than the rubber so a larger wheel with a smaller tyre reduces unsprung weight (note this doesn't apply to halfords range of fetching 'Fox' wheels ;-)). Take a look at Touring cars with 18' wheels and 30profile slicks.

Cheers Matt

Reply to
**-**

I agree that there may be these benefits, but if he started, say with

15", then his 16" (50 profile?) have already a lowered tyre profile and derive some of these benefits, sufficiently IMO. Going still further with yet lower profiles, and the ride might become unacceptably harsh.
Reply to
Johannes H Andersen

Depends what your aiming for really. Certainly with the road setup on my T16 its supple and comfortable (to me), this is with 17" Wheels and 205/40 tyres.

As with everything its a compromise with benefits and disadvantages.

Matt

Reply to
**-**

The gains in handling from the tires will only highlight the suspension weaknesses. To fully derive the handling benefits of the larger diameter magnesium rims, he would also have to upgrade the bushings, lower the suspension, upgrade the springs and struts. Then, these improvements would highlight the engine as needing upgrades. In the long run it would be less expensive to buy an SPG Turbo.

Reply to
ma_twain

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