17 inch wheels 981 S - will they fit?
Discussion
anonymous said:
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Agreed, it's the caliper which will (always) be the issue, never the discs themselves , but fact remains spacers might make the difference. In the case of the 981 the larger discs (rel 987) will make the minimum diameter necessary to clear the caliper greater. I don't know how the width of the caliper compares, but will likely affect the issue too.anonymous said:
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That would be true if the inner wheel was a fixed diameter and the top of caliper flat. Neither is the case so it may or may not be the case that spacers are critical. You will only find out by trying (or having engineering drawings). Personally having just looked at my 981S with its 18" winter wheels on, and measured the gap as best I can, it's a close call (there is about 1/2" clearance) and it wouldn't surprize me if spacers made the difference. 
Did we ever get to the bottom of this? I've put my 981 Boxster S to bed for winter, but recent cold weather got me wondering whether I could in theory put 17" wheels on with winter tyres. When I lived in Germany, I bought a set of 17" wheels with Michelin Alpin winter tyres for my E46 330 and they made a heck of a difference to driving in snow and even made driving on ice (gingerly) possible. I know my winter wheels with BMW bolt pattern won't fit the Porsche bolt pattern so it's not as easy as just trying it out. On the BMW 17" was the smallest wheel size that would fit over the 330s brakes and I think the 981s brakes are a little bigger. Still, they look tiny inside the 20" Sport Techno wheels I have fitted currently.
Interesting timing. I have just got a 17 inch 987 front wheel and it is sat here waiting for me to try it on the 981. No tyre on the wheel so I just want to see if it will fit over the brakes. I know you can fit 17 inch wheels on the 987 3.4S. If I feel brave I might get the jack out and try it but I'm worried about frost bite at the moment.
I had a set of 19 inch winters and also 18 inch winters. Both specific 981 wheels with correct n rated winter tyres. I've since started using the 18 inch winter wheels as summers so have some normal tyres fitted to them. I wanted the most narrow sizes I could find and also with the lowest load ratings. I went with Conti Premium Contact 6 in 215 45 and 245 45. Which now means I have no winter set for the car. Pics - of course -
I had a set of 19 inch winters and also 18 inch winters. Both specific 981 wheels with correct n rated winter tyres. I've since started using the 18 inch winter wheels as summers so have some normal tyres fitted to them. I wanted the most narrow sizes I could find and also with the lowest load ratings. I went with Conti Premium Contact 6 in 215 45 and 245 45. Which now means I have no winter set for the car. Pics - of course -
Looking at Design911's brake parts page for the 981 at https://www.design911shop.com/Porsche/Boxster-986-... I can see that the rear brake rotors of the 981 S are shared with the 987:
While the fronts are shared with the 997, 991 and the 2.0 718:
So I don't believe it's going to work on a Boxster S. I think an 18" wheel is the smallest that's going to fit although I'd love to be wrong about that!
While the fronts are shared with the 997, 991 and the 2.0 718:
So I don't believe it's going to work on a Boxster S. I think an 18" wheel is the smallest that's going to fit although I'd love to be wrong about that!
Short Answer - Yes
Long Answer
Caliper is hard up against the wheel inner face without a spacer. Hopefully you can see the distance between the wheel and the disc facing. Fine once I added a spacer I had lying around - not sure how thick. I spun the wheel around and nothing rubbed. You can hopefully see there is not much room between caliper and wheel barrel. Space between caliper and wheel inner face is obviously dependent on the size of spacer used. Took a few pics.
Long Answer
Caliper is hard up against the wheel inner face without a spacer. Hopefully you can see the distance between the wheel and the disc facing. Fine once I added a spacer I had lying around - not sure how thick. I spun the wheel around and nothing rubbed. You can hopefully see there is not much room between caliper and wheel barrel. Space between caliper and wheel inner face is obviously dependent on the size of spacer used. Took a few pics.
Very interesting - thanks for that ATM!
The thing that would worry me is that the very tight clearances don't leave much room for the inevitable bit of gravel to clear. And although it's not a common occurrence, I know it does happen because I've had stones stuck between brake rotor and heatshield enough times that I've had to do something about it. I seem to get one every 3-4 years, and those are just the ones that get stuck, so it must happen much more frequently. It would take just one bit of gravel to get wedged between caliper and wheel spoke, or between caliper and wheel drum to make your day a very bad one indeed. And I suppose it also depends on the inner diameter of the wheel drum. The 17" refers to the rim diameter, but this doesn't mean that the inner drum diameter is always going to be the same.
The thing that would worry me is that the very tight clearances don't leave much room for the inevitable bit of gravel to clear. And although it's not a common occurrence, I know it does happen because I've had stones stuck between brake rotor and heatshield enough times that I've had to do something about it. I seem to get one every 3-4 years, and those are just the ones that get stuck, so it must happen much more frequently. It would take just one bit of gravel to get wedged between caliper and wheel spoke, or between caliper and wheel drum to make your day a very bad one indeed. And I suppose it also depends on the inner diameter of the wheel drum. The 17" refers to the rim diameter, but this doesn't mean that the inner drum diameter is always going to be the same.
AW10 said:
You’ll need space for any wheel weights as well.
Oh yeah I forgot about this. Good shout - thanks. I'd probably have to get a wheel balancing guy to have a look before investing in tyres and what not. I might bolt on a set of used wheels and tyres and just try it. Although if comparing nice new 18 inch continental tyres [which I have now] with some older used tyres then I'm not sure how much difference I will feel or any improvement. We all know the 981 has some numbness in the steering. I'm hoping that lighter wheels with lighter thinner tyres at the front will improve feel - maybe even spacer'ed out more than necessary too will improve it even further.On my 996 the change from 18 to 17 made a massive difference [225 to 205] and then again when I added 15mm spacers to the front. I'm just not sure how much feedback the EPAS system can provide but surely every little helps. If an external force pushes the road wheels will it feedback to the steering wheel - surely it must.
ATM said:
We all know the 981 has some numbness in the steering. I'm hoping that lighter wheels with lighter thinner tyres at the front will improve feel - maybe even spacer'ed out more than necessary too will improve it even further.
A bit O/T but I've driven two 718 Boxster S and the 718 GTS 4.0 and they have much better steering despite still using EPAS. I've begun to investigate the possibility of using 718 steering parts (probably just the rack) to improve the steering on my 981. Considering that the 718's internal name is 981 and that many parts are shared between the two cars, I think there's a strong chance of success. Having said that, parts might need to be coded to the car and software locking is likely to be the biggest stumbling block...Gassing Station | Boxster/Cayman | Top of Page | What's New | My Stuff