Wheel Questions, Offsets and Spacers
05-25-2004, 10:00 AM
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Wheel Questions, Offsets and Spacers
Just a few questions about the wheel options on our cars, and what I should end up putting on the car.
Currently there is Design 90's, 16x7 front and 16x8 rear, on the car these have a 52.3mm offset, but the spacers on the car are 53mm wide themselves, so from what I understand this means that the wheels are out further than they should be, which would explain the heavy steering and the rear tyres rubbing on the fenders.
From what I gather the early models came either with 15x7 cookie cutters front and rear in 23.3mm offset and with a 21mm spacer at the rear, or 15x7 front and 15x8 rear fuchs, with 21.3mm and 10.6mm offset.
However the later cars didn't have the 21mm spacer at the rear with Phone Dials of the same size as the cookie cutters.
Anyhow, one of the D90's are cracked and I need to replace it, if I want to fix the offset up by getting new spacers it'll nearly cost more than getting a full set of new wheels, what I'd like is 15x7 front and 15x8 rear. I'd like them in the Fuchs with the proper offsets, but may need to go cookie cutters due to cost.
So
1. Why did they have the spacer on the rear in the early cars, and why did they remove it in the later ones?
2. If I go with cookie cutters and go 8" at the rear will having the extra offset compared to the fuchs of the same size be any problem?
Currently there is Design 90's, 16x7 front and 16x8 rear, on the car these have a 52.3mm offset, but the spacers on the car are 53mm wide themselves, so from what I understand this means that the wheels are out further than they should be, which would explain the heavy steering and the rear tyres rubbing on the fenders.
From what I gather the early models came either with 15x7 cookie cutters front and rear in 23.3mm offset and with a 21mm spacer at the rear, or 15x7 front and 15x8 rear fuchs, with 21.3mm and 10.6mm offset.
However the later cars didn't have the 21mm spacer at the rear with Phone Dials of the same size as the cookie cutters.
Anyhow, one of the D90's are cracked and I need to replace it, if I want to fix the offset up by getting new spacers it'll nearly cost more than getting a full set of new wheels, what I'd like is 15x7 front and 15x8 rear. I'd like them in the Fuchs with the proper offsets, but may need to go cookie cutters due to cost.
So
1. Why did they have the spacer on the rear in the early cars, and why did they remove it in the later ones?
2. If I go with cookie cutters and go 8" at the rear will having the extra offset compared to the fuchs of the same size be any problem?
05-25-2004, 11:09 AM
#2
Race Car
The '82-85.1 cars had cookie cutters in 15j7 all around with 23.3mm offset or 15j7&8 Fuchs with 23.3mm offset all around, I'm not sure what years they were available but there may have also been an option for 16j7 Fuchs with 23.3 offset all around. These cars had a 21mm spacer in the rear from the factory.
The '85.5-86 cars didn't have the spacer and it shows because the wheels are tucked under the fenders a bit further. the cookie cutters were replaced by the phone dials but the offsets remained the same. the 951 became available in '86 with either PDs or Fuchs in 16j7&8, the offset was 23.3mm all around and these wheels will also fit on an early NA. 10mm offset Fuchs are for 911s, I have them on the rear of my '86 NA because it brings the wheels back out to where they should be on my 'no spacer car," if you have the factory rear spacer I doubt they'd fit right.
I'm suprised that theres a rubbing issue with your current setup, if the stock 21mm spacer was replaced with a 53mm spacer there is a 32mm change in offset. Your wheels have a 29mm offset difference from stock wheels so yoyu'r really only off by 3mm! You didn't mention your tire size or alignment spec but I think there must be more to this rubbing than just the spacer. You also didn't mention how the front is set up.
The cost of spacers shouldn't realy be close to the cost of new wheels, especially if you're considering Fuchs.
Now I just gotta ask: How could your car have turbo bars from the factory if it was build 4 years before the turbo???
The '85.5-86 cars didn't have the spacer and it shows because the wheels are tucked under the fenders a bit further. the cookie cutters were replaced by the phone dials but the offsets remained the same. the 951 became available in '86 with either PDs or Fuchs in 16j7&8, the offset was 23.3mm all around and these wheels will also fit on an early NA. 10mm offset Fuchs are for 911s, I have them on the rear of my '86 NA because it brings the wheels back out to where they should be on my 'no spacer car," if you have the factory rear spacer I doubt they'd fit right.
I'm suprised that theres a rubbing issue with your current setup, if the stock 21mm spacer was replaced with a 53mm spacer there is a 32mm change in offset. Your wheels have a 29mm offset difference from stock wheels so yoyu'r really only off by 3mm! You didn't mention your tire size or alignment spec but I think there must be more to this rubbing than just the spacer. You also didn't mention how the front is set up.
The cost of spacers shouldn't realy be close to the cost of new wheels, especially if you're considering Fuchs.
Now I just gotta ask: How could your car have turbo bars from the factory if it was build 4 years before the turbo???
05-26-2004, 06:39 AM
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Ok the easy part first,
The turbo sway bars depends on what you use to decode the options, using the 944 FAQ options page it says it's the turbo sway bar option, using the decoder here at rennlist it just says they are larger sway bars.
The car is currently wearing Design 90 rims, 16x7 front and 16x8 rear, with 205/55 tyres front and 225/50 tyres rear. We put a set of calipers on the spacers on the car at the moment and they are 55mm wide, not 53mm wide, sorry bout that, my bad.
Now, the harder part, according to PET and 951 RacerX's site, http://members.rennlist.org/951_racerx/, the 15x8 Fuchs on the rear had an offset of 10.6mm, I was considering changing to the factory fuchs options for my car, but due to cost it looks like I'll have to go with Cookie Cutters.
Instead of going 7" wide all round I want to keep the widths I have now, 7" front and 8" rear, 205 and 225 tyres, except in 15" rims instead of 16". To keep the outside of the rear rims in about the same place as the standard 7" rims with the 21mm spacer I think I'd need a spacer about 0.5" or so smaller than the 21mm, or will it all work ok without any spacer at all since it is a wider rim width?
I really want to get rid of the current setup because the way we worked it out the way the front is setup is probably putting some funky forces on all the steering components and wheel bearings because as near as I can work out the offset at the front of the car could be out by 20 or 30 mm.
I only want to have to work all this out once and get it how it should be so I can just enjoy driving the car instead of worrying about (re)breaking rims and such, so anything anyone can add would be a huge help.
The turbo sway bars depends on what you use to decode the options, using the 944 FAQ options page it says it's the turbo sway bar option, using the decoder here at rennlist it just says they are larger sway bars.
The car is currently wearing Design 90 rims, 16x7 front and 16x8 rear, with 205/55 tyres front and 225/50 tyres rear. We put a set of calipers on the spacers on the car at the moment and they are 55mm wide, not 53mm wide, sorry bout that, my bad.
Now, the harder part, according to PET and 951 RacerX's site, http://members.rennlist.org/951_racerx/, the 15x8 Fuchs on the rear had an offset of 10.6mm, I was considering changing to the factory fuchs options for my car, but due to cost it looks like I'll have to go with Cookie Cutters.
Instead of going 7" wide all round I want to keep the widths I have now, 7" front and 8" rear, 205 and 225 tyres, except in 15" rims instead of 16". To keep the outside of the rear rims in about the same place as the standard 7" rims with the 21mm spacer I think I'd need a spacer about 0.5" or so smaller than the 21mm, or will it all work ok without any spacer at all since it is a wider rim width?
I really want to get rid of the current setup because the way we worked it out the way the front is setup is probably putting some funky forces on all the steering components and wheel bearings because as near as I can work out the offset at the front of the car could be out by 20 or 30 mm.
I only want to have to work all this out once and get it how it should be so I can just enjoy driving the car instead of worrying about (re)breaking rims and such, so anything anyone can add would be a huge help.
05-26-2004, 09:40 AM
#4
Race Car
I get it now!
My 16" Fuchs have the offset you mention because they're 911 wheels. 16" 951 wheels have 23.3mm all around, but I never really looked into the 15" Fuchs, I guess they just used the ones off the 911 at the time. This would be typical of Porsche since they use what they have and only make a different part if the one they already have doesn't fit (like 911 wheels over 951 brakes.
I have the same tire sizes that you have on my fuchs, I don't have any rear spacers ('85.5-'86 cars are the same as yours, but they didn't come with the 21mm spacers for some reason) and these tires fit nicely on my 911 offset wheels with no rubbing or anything. Ideally, I'd like to add a very thin spacer all around, ~7mm, but switching to 225/50 front and 245/45 rear is another posibility.
Speaking of 245's in the rear, a lot of guys run these on their stock wheels. Your 55mm spacer puts you 6mm closer to the fender lip than stock, a 245 would be 10mm closer than stock. If you have rubbing issues you better look into it because there might be something else to it.
I don't know anything about tire size and availability where you are, but here it isn't posible to keep the same size tires you have and go to 15" without getting things "a little funny." The sizes you'd need to do it right are not available. The stock size tires for 15j7 wheels all around is 215/60-15, IIRC Porsche still used this size all around for 7&8s. The stock tire diameter is 24.85", there arent a lot of choices out there. Some owners use 225/50-15, these are almost an inch smaller so they don't fit the wheel arches, they decrease fuel economy and throw the speedo off by a bit, they do lower the car a hair and should cause a slight improvement in acceleration but that is offset by more shifting. I have this size on 15j7 cookies for autocross use and I don't think it's an improvement, I will probably go larger when they wear out. There is no 205 width that matches this diameter, since the 225/50 is so much smaller around than the 215/60 I think the combination would look funny. When Porsche chose the 215/60-15 as the stock size they did a pretty good job, it's hard to improve on it.
My recommendation would be to find the wheels you want in either 7&8 or 7 all around and put either of these sizes at all four corners, don't worry about spacers yet (the last early offset cars didn't have them so the wheels will work without them) until you put the wheels on the car and you can see how much spacer you want to add in order to get the look the way you want it. I also would keep looking for Fuchs, you might find a great deal and they are a much higher quality wheel, and I'd encourage you to consider 16" Fuchs as well since you would be able to keep the staggered look that you seem to like and both the 911 and 951 wheels will bolt right up with no spacers (951 wheels will look better when used with a 12-21mm spacer though).
My 16" Fuchs have the offset you mention because they're 911 wheels. 16" 951 wheels have 23.3mm all around, but I never really looked into the 15" Fuchs, I guess they just used the ones off the 911 at the time. This would be typical of Porsche since they use what they have and only make a different part if the one they already have doesn't fit (like 911 wheels over 951 brakes.
I have the same tire sizes that you have on my fuchs, I don't have any rear spacers ('85.5-'86 cars are the same as yours, but they didn't come with the 21mm spacers for some reason) and these tires fit nicely on my 911 offset wheels with no rubbing or anything. Ideally, I'd like to add a very thin spacer all around, ~7mm, but switching to 225/50 front and 245/45 rear is another posibility.
Speaking of 245's in the rear, a lot of guys run these on their stock wheels. Your 55mm spacer puts you 6mm closer to the fender lip than stock, a 245 would be 10mm closer than stock. If you have rubbing issues you better look into it because there might be something else to it.
I don't know anything about tire size and availability where you are, but here it isn't posible to keep the same size tires you have and go to 15" without getting things "a little funny." The sizes you'd need to do it right are not available. The stock size tires for 15j7 wheels all around is 215/60-15, IIRC Porsche still used this size all around for 7&8s. The stock tire diameter is 24.85", there arent a lot of choices out there. Some owners use 225/50-15, these are almost an inch smaller so they don't fit the wheel arches, they decrease fuel economy and throw the speedo off by a bit, they do lower the car a hair and should cause a slight improvement in acceleration but that is offset by more shifting. I have this size on 15j7 cookies for autocross use and I don't think it's an improvement, I will probably go larger when they wear out. There is no 205 width that matches this diameter, since the 225/50 is so much smaller around than the 215/60 I think the combination would look funny. When Porsche chose the 215/60-15 as the stock size they did a pretty good job, it's hard to improve on it.
My recommendation would be to find the wheels you want in either 7&8 or 7 all around and put either of these sizes at all four corners, don't worry about spacers yet (the last early offset cars didn't have them so the wheels will work without them) until you put the wheels on the car and you can see how much spacer you want to add in order to get the look the way you want it. I also would keep looking for Fuchs, you might find a great deal and they are a much higher quality wheel, and I'd encourage you to consider 16" Fuchs as well since you would be able to keep the staggered look that you seem to like and both the 911 and 951 wheels will bolt right up with no spacers (951 wheels will look better when used with a 12-21mm spacer though).
