Cayenne wheels fit 944?
06-02-2005, 12:27 AM
#16
Burning Brakes
https://rennlist.com/forums/showthre...=wheel+weights
lists wheel and tire combined weights
89 Clubsport forged alloys w tires weigh 16x7/42lbs and 16x9/46lbs
(being replaced this week with Dunlop SPs)
lists wheel and tire combined weights
89 Clubsport forged alloys w tires weigh 16x7/42lbs and 16x9/46lbs
(being replaced this week with Dunlop SPs)
Last edited by steve g; 06-02-2005 at 11:10 PM.
06-02-2005, 05:40 AM
#17
Race Director
"Using common sense alone, I think that a wheel with zero offset would be ideal. Can anyone confirm?"
Well, a wheel with straight flat spokes directly between the rim-edges with zero offset would probably be the lightest and strongest wheel possible, but there are other compromises when you install that wheel onto a car.
It has to do with centering the rim's centerline between the inner and outer wheel-bearings. The thickness of the hub determines offset as well. So if you can place the wheel's centerline directly between the two bearings, that would be ideal for vertical loads and straight-line driving. The offset is then to center the wheel after you added in the thickness of the hub; early car had thinner hubs so less offset is needed to center the wheels over the bearings. The later cars with thicker hubs needed more offset to re-center the wheel over the bearings.
However, perfectly even bearing loads to carry the weight of the car in a straight line is one thing, but cornering-loads really tax the outer bearing. So you can kind of balance that out by having wheels with extra offset that puts the centerline of the wheel inwards of the bearings. This then loads the inner bearing more in straight-line driving but evens it out with less outer-bearing loads under cornering (compared to a perfectly centered wheel).
"I was under the imperssion that having wheels in different offset positions could change the handling and also prematurely add wear and tear on certain hardware pieces. I.e a positive offset could actually could wear out bearings and tires prematurely. Is this not true?"
Again, this has to do with how your new wheels and their effective offsets compare to stock. Once you've bolted a wheel to the hub, the wheel, hub, studs, spacers if any, are all effectively one solid assembly. The alignment of this assembly relative to the bearings then detemrine the loads on those bearings. Ideally, you would set up offsets such that the bearings are perfectly centered between the rim-edges. If the bearings are inboard of the wheel's centerline, it tends to cause the wheel to rock inwards at the top and cause a lateral torque on the bearings. Conversely, if the bearings are outboard of the centerline, the wheel will rock outwards.
In upgrade situations, you want to configure the wheel to have similar offsets to stock to keep the bearing loads and suspension geometry similar to stock. But, that's not always possible, so it's better to actually have too much offset and have the wheel sit to far inwards than having too little offset. The detrimental effects on bearing loads, steering-geomtry and fender clearances are much less with having too much offset compared to having too little offset. Plus with too much offset, you can always move the wheel outwards with spacers into the most optimal position whereas with too little offset, you end up rubbing the fenders and there's absolutely nothing you can do except to run narrower tires.
Well, a wheel with straight flat spokes directly between the rim-edges with zero offset would probably be the lightest and strongest wheel possible, but there are other compromises when you install that wheel onto a car.
It has to do with centering the rim's centerline between the inner and outer wheel-bearings. The thickness of the hub determines offset as well. So if you can place the wheel's centerline directly between the two bearings, that would be ideal for vertical loads and straight-line driving. The offset is then to center the wheel after you added in the thickness of the hub; early car had thinner hubs so less offset is needed to center the wheels over the bearings. The later cars with thicker hubs needed more offset to re-center the wheel over the bearings.
However, perfectly even bearing loads to carry the weight of the car in a straight line is one thing, but cornering-loads really tax the outer bearing. So you can kind of balance that out by having wheels with extra offset that puts the centerline of the wheel inwards of the bearings. This then loads the inner bearing more in straight-line driving but evens it out with less outer-bearing loads under cornering (compared to a perfectly centered wheel).
"I was under the imperssion that having wheels in different offset positions could change the handling and also prematurely add wear and tear on certain hardware pieces. I.e a positive offset could actually could wear out bearings and tires prematurely. Is this not true?"
Again, this has to do with how your new wheels and their effective offsets compare to stock. Once you've bolted a wheel to the hub, the wheel, hub, studs, spacers if any, are all effectively one solid assembly. The alignment of this assembly relative to the bearings then detemrine the loads on those bearings. Ideally, you would set up offsets such that the bearings are perfectly centered between the rim-edges. If the bearings are inboard of the wheel's centerline, it tends to cause the wheel to rock inwards at the top and cause a lateral torque on the bearings. Conversely, if the bearings are outboard of the centerline, the wheel will rock outwards.
In upgrade situations, you want to configure the wheel to have similar offsets to stock to keep the bearing loads and suspension geometry similar to stock. But, that's not always possible, so it's better to actually have too much offset and have the wheel sit to far inwards than having too little offset. The detrimental effects on bearing loads, steering-geomtry and fender clearances are much less with having too much offset compared to having too little offset. Plus with too much offset, you can always move the wheel outwards with spacers into the most optimal position whereas with too little offset, you end up rubbing the fenders and there's absolutely nothing you can do except to run narrower tires.
