18 inch wheels on a 84 n/a
08-20-2007, 01:46 AM
#16
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Porsche advises against fitting the 944/968 cars with anything over 17" and these should go together with a 968 caster block upgrade.
Eventually, larger wheels put too much stress on the front control arm ball joints, tend to hit the fenders, etc. You can get away with the fronts if you have billet aluminum Charley Arms. YMMV
Eventually, larger wheels put too much stress on the front control arm ball joints, tend to hit the fenders, etc. You can get away with the fronts if you have billet aluminum Charley Arms. YMMV
08-20-2007, 11:30 AM
#17
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I am not a big fan of bigger wheels -
1. Larger unsprung weight is the worst additional wieght you can have on your car.
2. As mentioned, if you're running stock A-arms and castor blocks, you are further stressing this point with larger wheels, especially if you've lowered your car.
3. Also as already mentioned - the probability of a bent rim is greater with a larger diameter wheel due to the smaller sidewalls of the tires.
That being said, there are reasons for getting larger wheels -- the most logical one I can think of is to fit bigger brakes under them. (Side note: I found out accidentally, that 993 Twin turbo calipers will not fit under the stock 16-inch wheel on my 944S2 -- I had my shop upgrade my brakes to the 944 Turbo S clampers, and their supply house accidentally shipped the 993 turbo calipers...)
But then again, unless you have a turbo that's putting out massive power, you don't really need anything more than the normal 944 Turbo brakes...
My $0.42,
-Z-man.
08-20-2007, 12:14 PM
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remember that contact patch area does not change, only the shape, because the weight of the vehicle stays the same.
wider tires with a small sidewall will have a rectangular contact patch, narrow but long. (perpendicular to the car)
skinnier tires with bigger sidewalls will have a more square contact patch.
skinnier tires are more flexible, and work better with softly sprung cars, a prime example are stock cars
the sidewall allow for the contact patch to stay on the ground even if the car rolls alot, so even if you as a driver feel like you are about to fly out the window, the car is still gripping the road, this is whats known as road holding
however many people dont realize it and instead try to focus on flat, flat, flat and more flat cornering.
a wide tire with its narrow but long contact patch is more stable, partly because of the small sidewall, partly because of the side forces generated through that thin but long contact patch make it more stable (as was explained to me)
however the problem with too wide a tire on a car with the suspension not setup correctly (ie, really good geometry, stiff springs and lot and lots of proper aero) is that the car will tilt on the tire itself, reducing your contact patch and making 30% of your tire utterly useless and at that point complete dead weight.
wider tires dont automaticaly give you more grip, there are many variables that have to be put into account to actualy prove that
but, as i said before, what often happens when people put on low profile wide tires is the increased feeling of flatness, which alot of amateure racers seem to associate with increased performance, when really its mostly to do with the fact that they are not being throw around in their chair, allowing them to focus more on the driving.
