17 inch wheels 981 S - will they fit? - Page 3 - Boxster/Cayman - PistonHeads UK

Hello Does anyone know if a 17 inch wheel will fit the 981? TIA

Don't think so. Brake fouling.....

Poo Are the discs really that big?

ATM said: Poo Are the discs really that big? I think so, why do you want to? (Apart from the fact that winter wheel and tyre sets are dirt cheap in 17", distinctly more expensive in 18" and ridiculous in larger sizes).

bcr5784 said: I think so, why do you want to? (Apart from the fact that winter wheel and tyre sets are dirt cheap in 17", distinctly more expensive in 18" and ridiculous in larger sizes). This. 17 inch wheels on ebay go for peanuts because no one wants them - clearly. I've not really decided what to do so just looking at options. If I'm honest the car drives better than I expected considering they're 20 inch wheels. Therefore it would obviously drive better on 19 and even better on 18. Read some interesting blurb about the wheel and tyre combos weighing pretty much the same for 18, 19 and 20. It seems the wheels get heavier but the tyres get lighter.

ATM said: This. 17 inch wheels on ebay go for peanuts because no one wants them - clearly. I've not really decided what to do so just looking at options. If I'm honest the car drives better than I expected considering they're 20 inch wheels. Therefore it would obviously drive better on 19 and even better on 18. Read some interesting blurb about the wheel and tyre combos weighing pretty much the same for 18, 19 and 20. It seems the wheels get heavier but the tyres get lighter. Check with your insurers before fitting anything differing from standard spec 18, 19, or 20 inch wheels/tyres. Smaller wheels don't equal "better". More comfy over bumps perhaps, but at the expense of cornering performance and feel.

ATM said: This. 17 inch wheels on ebay go for peanuts because no one wants them - clearly. I've not really decided what to do so just looking at options. If I'm honest the car drives better than I expected considering they're 20 inch wheels. Therefore it would obviously drive better on 19 and even better on 18. Read some interesting blurb about the wheel and tyre combos weighing pretty much the same for 18, 19 and 20. It seems the wheels get heavier but the tyres get lighter. A problem with 17 inch wheels is that you won't be able to use the latest tyre technology e.g. Michelin supersports and pilot sport cup 2 are not made for anything smaller than 18 inch.

I started the thread thinking about Winter tyres. Now I am also thinking about Summers. The ride is better than I thought it would be on 20 inch wheels. The car has masses of grip now even on these cool, damp and gritty roads. It does get a bit unsettled and jiggly on bumpy roads. This would probably be improved with a bit less tyre wall stiffness.

ATM said: I started the thread thinking about Winter tyres. Now I am also thinking about Summers. The ride is better than I thought it would be on 20 inch wheels. The car has masses of grip now even on these cool, damp and gritty roads. It does get a bit unsettled and jiggly on bumpy roads. This would probably be improved with a bit less tyre wall stiffness. I have a set of Goodyear Eagle F1s (N0) tyres 235/45 and 265/45s for 18 wheels. They came off a near new vehicle and have covered only a nominal mileage (I had the rims fitted with winter tyres - but we haven't had any cold weather yet!) If you go down the 18" wheel route to get the best ride (and a bit less noise) and are looking for some tyres PM me

anonymous said: [redacted] No, correct. A quick Google... "Small sidewalls are very stiff, great for cornering "feel" but terrible for ride quality..." just as I said. From: http://www.tuneruniversity.com/blog/2011/04/wheel-... There are many arguments for choosing large or small wheels, I just mentioned one from each side to get the OP thinking. The above article lists just about every other reason for choosing one or the other.

So they do fit then?

Bennachie said: So they do fit then? Well the poster above who has 17 inch wheels on a Caymen has the previous 987 type model.

anonymous said: [redacted] I've driven 981s on 18, 19 and 20" wheels and my findings accord with conventional wisdom - lower profile tyres on bigger rims give sharper steering, a worse ride and a bit more road noise. I can't see why that would change on 17s unless there was a change of tyre brand or type. In any case I would be wary of going away from Porsche approved tyres while the car was under warranty.

ATM said: Outside warranty - just. I've read people comment that the combo of 20 wheels and pasm has an acceptable ride. I don't have pasm and find the ride quite jiggle and unrefined. I'm sure the ride in my 997 with pasm and 19 wheels felt better. I've always liked the way Porsche cars feel well damped and composed when you're just pottering around. This does not. I doubt I will ever get to anywhere near 9 tenths of the cars ability at the limit. So for me the enjoyment is the from the mundane stuff where I am only getting from a to b but hopefully enjoying it a bit because I enjoy pottering in a more well rounded package. You may well have tried this already - but if not it's probably worth trying the "comfort" tyre pressure settings for your 20" wheels. Normal setting is 33psi "comfort" 30psi. You will be limited to 165mph - but you might just find you can live with that.

ATM said: Update I am now a bit happier with the comfort setting. It's hard keeping below 165 mph most of the time. I decided my Pirelli tyred looked a bit tired. They have plenty of tread and are dated 2013. I found some used MPSS dated 2015 to fit the rears. I'm glad I did this because my tyre guy found one of the wheels is buckled. I didn't get to see it spinning myself so I might have to jack the back up and spin the wheels in gear. Anyway the MPSS feel a bit better. They seem to give more of a thud than a crash on bumps. I could be imagining it obviously. Anyway this has brought me back round to wheel size dilemmas. A replacement 20 inch wheel is going to be 500 - 800 and I now want 4 new tyres too. I'm tempted to try 18 but the correct 981 wheels are not exactly plentiful. I might get some from the previous gen car which have very similar width and offset. Obviously the previous gen car has the wrong tyre size. I'll probably go with MPSS as everyone raves about them. I am also tempted to try cups as they're available in the correct 18 size but I'll probably wimp out. I can't imagine I really need that much grip especially if I stay below 165 mph. Another bit of grist to the mill. Though I'm no great fan of Pirellis I have to say on 19" wheels bump thump (not sure if that is a technical term - but was used by car mags regularly in the past) is VERY well suppressed on Pirellis - though tyre roar on coarse surfaces is dreadful. 18" Eagles produce an even better ride than 19" - mostly at the front (I have a set of practically new tyres, of the right size, if you are interested, but I am using the wheels for winter tyres) . Personally it's so good with PASM on 19s that I wouldn't go below that myself.

bcr5784 said: Another bit of grist to the mill. Though I'm no great fan of Pirellis I have to say on 19" wheels bump thump (not sure if that is a technical term - but was used by car mags regularly in the past) is VERY well suppressed on Pirellis - though tyre roar on coarse surfaces is dreadful. 18" Eagles produce an even better ride than 19" - mostly at the front (I have a set of practically new tyres, of the right size, if you are interested, but I am using the wheels for winter tyres) . Personally it's so good with PASM on 19s that I wouldn't go below that myself. I'm not sure if the bump thump change is due to the old tyres being a bit old. Tyres do go hard with age which is why you cant beat some brand new boots. I've punched the numbers in for the 987 17 inch fronts here and the difference is not that big: http://www.willtheyfit.com/index.php?width=205&amp... Rears are a bit further out: http://www.willtheyfit.com/index.php?width=235&amp...

ATM said: I'm not sure if the bump thump change is due to the old tyres being a bit old. Tyres do go hard with age which is why you cant beat some brand new boots. I've punched the numbers in for the 987 17 inch fronts here and the difference is not that big: http://www.willtheyfit.com/index.php?width=205&amp... Rears are a bit further out: http://www.willtheyfit.com/index.php?width=235&amp... It's not just the tyre diameter that is the issue - it's whether the wheels will clear the brake calipers. I've never tried it - but from what others have said - I suspect you would need wheel spacers at least. There's not that much room on 18s.

bcr5784 said: ATM said: I'm not sure if the bump thump change is due to the old tyres being a bit old. Tyres do go hard with age which is why you cant beat some brand new boots. I've punched the numbers in for the 987 17 inch fronts here and the difference is not that big: http://www.willtheyfit.com/index.php?width=205&amp... Rears are a bit further out: http://www.willtheyfit.com/index.php?width=235&amp... It's not just the tyre diameter that is the issue - it's whether the wheels will clear the brake calipers. I've never tried it - but from what others have said - I suspect you would need wheel spacers at least. There's not that much room on 18s. I'm still not convinced. According to this Porsche press sheet the front discs are 13.0 x 1.1-in. In my mind 13 inch discs are 330 mm. I have some 355mm discs on my e46 which apparently can fit under some 17 inch wheels - or so I've read. I've used 2 different sets of 18 inch wheels on the e46 myself with these 355mm discs. One was tight and the current OZ's have a bit more room. Anyway a 330mm disc is an inch smaller. So I think a 17 inch wheel will go over the disc and caliper. I'll accept there might be a clearance issue where the face of the wheel meets the hub but that is just a spacer to fix. http://press.porsche.com/vehicles/2013/2013_Boxste...

ATM said: I'm still not convinced. According to this Porsche press sheet the front discs are 13.0 x 1.1-in. In my mind 13 inch discs are 330 mm. I have some 355mm discs on my e46 which apparently can fit under some 17 inch wheels - or so I've read. I've used 2 different sets of 18 inch wheels on the e46 myself with these 355mm discs. One was tight and the current OZ's have a bit more room. Anyway a 330mm disc is an inch smaller. So I think a 17 inch wheel will go over the disc and caliper. I'll accept there might be a clearance issue where the face of the wheel meets the hub but that is just a spacer to fix. http://press.porsche.com/vehicles/2013/2013_Boxste... All I can say is that I'm pretty sure someone said spacers were needed to fit 17s on a 987 S which has 318mm front discs, so 330mm discs are bound to be a bit tight - even wheel weights may be an issue.

bcr5784 said: All I can say is that I'm pretty sure someone said spacers were needed to fit 17s on a 987 S which has 318mm front discs, so 330mm discs are bound to be a bit tight - even wheel weights may be an issue. I think that was the moose of C. He runs tiny wheels on his gay-man.

anonymous said: [redacted] Obviously they CAN. The INSIDE of the wheel is not a fixed diameter, but is larger at the inner end. So if you are close to the margin spacers might help. Whether they would make the difference in this case is obviously open to question.

anonymous said: [redacted] 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: [redacted] 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.

anonymous said: [redacted] As you say your usual insanity - not mine. Fact is it may fit, spacers might help, but I wouldn't buy 17" wheels without trying them first.

bcr5784 said: anonymous said: [redacted] As you say your usual insanity - not mine. Fact is it may fit, spacers might help, but I wouldn't buy 17" wheels without trying them first. This is a good idea. Moose where do you reside - roughly?

ATM said: This is a good idea. Moose where do you reside - roughly? I'm led to believe Bedlam - seems plausible.

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 -

ATM said: It has to be done. It's christmas.

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!

I think the Callipers on the front of the 981 are quite slimline. The only way to know is try a wheel.

FWIW my 18" winter set fits fine over 981 PCCBs. The ride with PASM is similar to the normal 20"s, if a little 'squidgier'.

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.

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.

In all my life I have never had a problem with gravel getting stuck in a wheel or disc or anything like that. Most of my cars run smaller wheels now with less clearances. I would not be concerned. But I live in a city with tarmac roads so no gravel.

If you could see some of the roads I found myself on in September last year on my France and Spain road trip, you'd know why I'm cautious!

Gravel/calliper/rim issues can occur, as I know from PCCB/20 inch 991 experience…

You’ll need space for any wheel weights as well.

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...

LunarOne said: 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... 718 internal code is 982, not 981. It is a facelift of the 981 - really a 981.2. But I think your problem is going to be software. A lot of the 'feel' is in the code, it's not real road feel, it's coded force feedback. And in any case, the rack would certainly need to be coded to the car. Can a 981 run 982 steering rack code? It'll need to, to work. Moreover, on the 987.2, I believe to fit a used rack (believe it or not, even on a 987.2 the rack needs to be coded to the car), you also need to replace the main ECU and the steering column ECU as a trio. And then recode the lot. So, it's a nightmare. Using a brand new rack I [i]think{/i] may allow the fitting of just the rack on a 987.2. Not sure about the 981/982. But my guess is that you'll find it's either a nightmare or impossible. Good luck, report back if you succeed!

MA121C said: LunarOne said: 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... 718 internal code is 982, not 981. It is a facelift of the 981 - really a 981.2. But I think your problem is going to be software. A lot of the 'feel' is in the code, it's not real road feel, it's coded force feedback. And in any case, the rack would certainly need to be coded to the car. Can a 981 run 982 steering rack code? It'll need to, to work. Moreover, on the 987.2, I believe to fit a used rack (believe it or not, even on a 987.2 the rack needs to be coded to the car), you also need to replace the main ECU and the steering column ECU as a trio. And then recode the lot. So, it's a nightmare. Using a brand new rack I [i]think{/i] may allow the fitting of just the rack on a 987.2. Not sure about the 981/982. But my guess is that you'll find it's either a nightmare or impossible. Good luck, report back if you succeed! Ah yes, I thought I typed 982 but it came out as 981. I wasn't aware that there is a steering column ECU as well as the rack, but I agree that the biggest issue is likely to be software. Perhaps some Porsche specialists with the right PIWIS tools might be able to do the coding, I'm not sure. But I have started investigating.

The point re the 987.2 is that to fit a used rack, you need to fit the main ECU and steering column ECU with the rack, all sourced from the same car. You apparently can't just recode a used rack to a car on its own. So, you'll find breakers flogging the set - rack, main ECU and steering column key switch with the ECU - as a job lot. It seems unlikely the 981/982 will be less complex... As an alternative, what rack does the 991.1 GT3 use? Might be the same rack as the 981. In which case you'd then only need to see if you can use the GT3 steering map. Been a while since I drove a 991.1 GT3, but pretty sure it has better feel than a 981. I did once dig around to see if you could use GT3 steering mapping on a 981, but couldn't find anything. Would be simpler than swapping the rack out AND doing the recoding, anyway. But I suspect you'll find either option is super hard or impossible.

MA121C said: As an alternative, what rack does the 991.1 GT3 use? Might be the same rack as the 981. In which case you'd then only need to see if you can use the GT3 steering map. Been a while since I drove a 991.1 GT3, but pretty sure it has better feel than a 981. I'm not convinced that all of the feel of an ePAS system comes from software. After all, forces are still transmitted through the wheels, the tie rods, the rack, up the steering column and to the steering wheel even when powered assistance isn't working, either because it's failed or because there's no power to make it work, for example in the case of a failed alternator and flat battery. There is still the same mechanical connection as there is in a traditional hydraulic system, it's just that the assistance is provided differently. Since the mechanical connection is still there, why does it feel different? Is it because the electrical system's software is damping out forces transmitted from the road? Possibly. But I'm sure the hardware is different, because the steering weighting and feel is so markedly different between the 981 and 982. Given all the criticism of the 981's less than stellar steering, you'd have thought that Porsche would have fixed it with a software update if they could have. That's why I'm convinced that a large component of the feel comes from the hardware, and the only hardware factors that could markedly affect it are steering geometry such as wheel size and offsets, distance from the wheel turning centres to the steering ball joint, and relative position and length of the rack, and the rack ratio itself.

Doesn’t the 981 Spyder (and probably the 981 GT4) use a different rack than the rest of the 981 series? presumably they have better feedback?

Feedback can also by a symptom of geo. Massive negative camber will give more feedback - caster too maybe. I think the latest GT3 cars use rose joints instead of rubber bushes.

I'm pretty sure the GT3 cars use double-wishbone suspension rather than the MacPherson struts seen on lower 991s, GT4s and all other Caysters, so the geometry is going to be different (at least at most front suspension travel positions). Double wishbones keep the camber angles much more precisely under control, whereas it varies much more as the wheel travels up and down relative to the car with MacPherson struts. Also, the GT cars have user-adjustable suspension whereas the lower cars don't.

No, double wishbone front first appeared on the 992 GT3. 991 GT3 is strut. GT4 uses the 991 GT3 front struts. The 982 has a different rack from the 981. But the question remains re 991.1 GT3. If it uses the same rack as the 981, that might be a much easier route to better feel. Wasn't saying all the feel is in the map. But a lot of it is. And like I said, if you could put the GT3 map onto your car, that might well be the most effective way to improve things. Changing the rack itself to one from a later generation of car I suspect will only be harder in terms of the software problem. Which may be insoluble in any case whichever way you go at it.