Wheel Advice Needed For '89 S2: 7" Front/8" Rear (stock Size), or 8" Front/9" Rear?
10-02-2018, 04:14 AM
#1
Wheel Advice Needed For '89 S2: 7" Front/8" Rear (stock Size), or 8" Front/9" Rear?
https://www.fuchsfelgeusa.com/wheel/...e%2Dfuchs%2D17
The 7/8's are the exact sizes and offsets that came stock on my '89 S2, while the 8/9's would be 3mils added (that is, the wheel would be three mils closer to the inner fender from the stock position) up front and 3mils further inward from the fender in the back. I can't imagine that minor of a difference in offset would be an issue (it's only .12"), but I'm a novice and know nothing, so any experienced opinion is greatly appreciated. Weight difference between the two sets is only a pound, so not much of an problem there, though the larger tires would add some extra weight.
The 7/8's are the exact sizes and offsets that came stock on my '89 S2, while the 8/9's would be 3mils added (that is, the wheel would be three mils closer to the inner fender from the stock position) up front and 3mils further inward from the fender in the back. I can't imagine that minor of a difference in offset would be an issue (it's only .12"), but I'm a novice and know nothing, so any experienced opinion is greatly appreciated. Weight difference between the two sets is only a pound, so not much of an problem there, though the larger tires would add some extra weight.
10-02-2018, 08:12 AM
#2
It depends what you want. I have 7Jx16" front and 8Jx16" tele dials rear for the summer and 7.5Jx17" front and 9Jx17" Migle Miglia Cup1. Car is much more planted with the wider wheels, also I feel that it cares less about potholes etc. it's more like hammer. At the same time this dude uses 15"
teledials and I heard from him that it's less mass to be rotated, car is more nimble.
Personally I would go for 8J and 9J with 225 fronts and 255 rears if you are not competing very often or you are competing on high speed courses.
Personally I would go for 8J and 9J with 225 fronts and 255 rears if you are not competing very often or you are competing on high speed courses.
10-02-2018, 11:07 AM
#3
Instructor
You need to check your math, even though the offset is only 3mm different, the width is an extra +25.4. With the +3mm offset, you have 9.7mm (~3/8") additional toward the outside and 15.7mm (~5/8") additional on the inside. In the front you will have 12.7mm (1/2") each way.
Some modification may be needed to make them fit, though I believe plenty of 944 owners run these widths. Measure twice.
In my opinion, the wheels are all about the look (and the 17" Fuchsfelge have a wonderful look). Do lots of research to make sure it is what you want. Upsizing wheels will not net you a performance gain. Larger wheels = more rotational inertia to get moving and slow down. Wider tires = more contact patch, but only needed for very high performance driving and must be done to suit the driver. The staggered widths of the stock sizes will cause the car to understeer more than a square setup. So it comes down to what your intentions are. Want the look? Go for it. Want performance? Rethink your approach.
Some modification may be needed to make them fit, though I believe plenty of 944 owners run these widths. Measure twice.
In my opinion, the wheels are all about the look (and the 17" Fuchsfelge have a wonderful look). Do lots of research to make sure it is what you want. Upsizing wheels will not net you a performance gain. Larger wheels = more rotational inertia to get moving and slow down. Wider tires = more contact patch, but only needed for very high performance driving and must be done to suit the driver. The staggered widths of the stock sizes will cause the car to understeer more than a square setup. So it comes down to what your intentions are. Want the look? Go for it. Want performance? Rethink your approach.
10-02-2018, 05:30 PM
#4
You may also compare it to factory wheels available for 944: http://www.944racing.de/wheelweights.php
and what Porsche says about it: https://www.porsche.com/internationa.../tyreapproval/
and what Porsche says about it: https://www.porsche.com/internationa.../tyreapproval/
Last edited by Duke48; 10-02-2018 at 06:02 PM.
10-02-2018, 08:56 PM
#5
You need to check your math, even though the offset is only 3mm different, the width is an extra +25.4. With the +3mm offset, you have 9.7mm (~3/8") additional toward the outside and 15.7mm (~5/8") additional on the inside. In the front you will have 12.7mm (1/2") each way.
Some modification may be needed to make them fit, though I believe plenty of 944 owners run these widths. Measure twice.
In my opinion, the wheels are all about the look (and the 17" Fuchsfelge have a wonderful look). Do lots of research to make sure it is what you want. Upsizing wheels will not net you a performance gain. Larger wheels = more rotational inertia to get moving and slow down. Wider tires = more contact patch, but only needed for very high performance driving and must be done to suit the driver. The staggered widths of the stock sizes will cause the car to understeer more than a square setup. So it comes down to what your intentions are. Want the look? Go for it. Want performance? Rethink your approach.
Some modification may be needed to make them fit, though I believe plenty of 944 owners run these widths. Measure twice.
In my opinion, the wheels are all about the look (and the 17" Fuchsfelge have a wonderful look). Do lots of research to make sure it is what you want. Upsizing wheels will not net you a performance gain. Larger wheels = more rotational inertia to get moving and slow down. Wider tires = more contact patch, but only needed for very high performance driving and must be done to suit the driver. The staggered widths of the stock sizes will cause the car to understeer more than a square setup. So it comes down to what your intentions are. Want the look? Go for it. Want performance? Rethink your approach.
As to mass, the 17" Fuchs are actually lighter than stock 16", but obviously the tires are going to weigh more, so it's either a wash or a negative (almost certainly a negative give the weight of tires). But aesthetics is my motivating factor.
10-02-2018, 11:23 PM
#6
Hates Family Guy
Rennlist Member
Rennlist Member
You're right, ET is the difference from the centerline of the wheel to the mounting surface. But you're looking at wider wheels, so you have to lose clearance somewhere. If you have an 8" ET 0 wheel, the face of the wheel is 4" from the mounting surface, and the back of the wheel is 4" from the mounting surface. Now you move up to a 9" wheel, same offset. The face of the wheel is now 4.5" from the mounting surface, or 0.5" closer to the fender, and the back is also 4.5" from the mounting surface, or 0.5" closer to the strut. If it's too close to the strut or hits something inside when turning you can add a spacer or get a wheel with less offset, but that's going to move the wheel closer to the fender. If it is too close to the fender you can get a wheel with more offset, or maybe roll your fender to gain clearance. Got it?
10-03-2018, 01:00 AM
#7
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10-03-2018, 01:36 AM
#8
Hates Family Guy
Rennlist Member
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I blame Jimmy Carter. One inch is 25.4 mm. Your 8/9 setup is 25.4mm wider than a 7/8 setup. So as I explained above, a one inch wider wheel with the same offset is 1/2" closer to the strut, and 1/2" closer to the fender. Or to put it another way, 12.7mm closer to the strut and 12.7mm closer to the fender. Calculate in the change in offset and you have the numbers Screamin came up with above.
10-03-2018, 08:21 AM
#9
Instructor
Its not the change in offset, it is the change in width that makes the biggest difference. That extra 25.4mm of width has to go somewhere.
10-03-2018, 05:59 PM
#10
I blame Jimmy Carter. One inch is 25.4 mm. Your 8/9 setup is 25.4mm wider than a 7/8 setup. So as I explained above, a one inch wider wheel with the same offset is 1/2" closer to the strut, and 1/2" closer to the fender. Or to put it another way, 12.7mm closer to the strut and 12.7mm closer to the fender. Calculate in the change in offset and you have the numbers Screamin came up with above.
10-03-2018, 10:50 PM
#11
If you have non-M030 struts, it is going to be very tight fitting an 8" wheel on the front.
You could measure the existing wheel, and do the math to see if it fits; compensating for how the rolled bead on the wheel extends past the nominal width. You need to leave some room for error because the bead dimension is not going to be identical between all wheels.
You could measure the existing wheel, and do the math to see if it fits; compensating for how the rolled bead on the wheel extends past the nominal width. You need to leave some room for error because the bead dimension is not going to be identical between all wheels.
10-05-2018, 02:38 AM
#12
If you have non-M030 struts, it is going to be very tight fitting an 8" wheel on the front.
You could measure the existing wheel, and do the math to see if it fits; compensating for how the rolled bead on the wheel extends past the nominal width. You need to leave some room for error because the bead dimension is not going to be identical between all wheels.
You could measure the existing wheel, and do the math to see if it fits; compensating for how the rolled bead on the wheel extends past the nominal width. You need to leave some room for error because the bead dimension is not going to be identical between all wheels.