joeluth Posted September 6, 2021 Report Share Posted September 6, 2021 (edited) Hi, my 986 Boxster came with the 17" "Boxster II" alloys - just like these ones - Front 6.5x17 (ET 55) 205.55.17 Rear 8x17 (ET40) 235.50.17 I looked up what the approved wheel and tyre combo was in the Boxster Bentley manual and found: Front 7 x17 (ET55) 205/50/17 Rear 8.5x17 (ET48/50) 255/40/17 Quite different!.. so after a bit of research I discovered my wheels are from a 987 Boxster / Cayman, see below. Not sure if I should be bothered that these aren't quite the right wheels, but I want to get a new set of tyres and get it right! I was thinking Pilot Sport 4 is the way to go, but they don't do that exact size tyre, seems I'd have to get a slightly lower profile at 50 on the front and 45 at the back. Sorry for rambling on, I guess really my questions are: Does it matter that I have 987 wheels on my 986? & should I care that the pilot sports are only available in with a lower profile (5 less front and back)? Thanks!! Edited September 6, 2021 by joeluth Quote Link to comment Share on other sites More sharing options...
½cwt Posted September 6, 2021 Report Share Posted September 6, 2021 Check in the Driver Manual, it lists all the tyre and rum combinations. That said, I'm running 996 wheel sizes on my 986 with no problem. The only issue is as you have found might be getting N spec but then again the N spec tyres for the 986 are so old in design that newer non N designs are as good, if not better. Quote Link to comment Share on other sites More sharing options...
Menoporsche Posted September 6, 2021 Report Share Posted September 6, 2021 My guess is their race-tested tyre specs on brand new cars give different results to you driving around roads on tired suspension components, to put it politely You are right to ask but don't stress to the Nth degree (oh damn that was witty...) Quote Link to comment Share on other sites More sharing options...
joeluth Posted September 6, 2021 Author Report Share Posted September 6, 2021 44 minutes ago, Menoporsche said: My guess is their race-tested tyre specs on brand new cars give different results to you driving around roads on tired suspension components, to put it politely You are right to ask but don't stress to the Nth degree (oh damn that was witty...) Lol! My suspension components are (mostly) brand new I'll have you know! But yeah point taken.. Quote Link to comment Share on other sites More sharing options...
joeluth Posted September 6, 2021 Author Report Share Posted September 6, 2021 1 hour ago, ½cwt said: Check in the Driver Manual, it lists all the tyre and rum combinations. That said, I'm running 996 wheel sizes on my 986 with no problem. The only issue is as you have found might be getting N spec but then again the N spec tyres for the 986 are so old in design that newer non N designs are as good, if not better. Ah, yes I did but as I have a 986 manual the wheel dimensions are different. I found the 987 manual online and found my wheels and tyre size listed as "Summer Tyres" so there's a solid reference that the current tyres are correct, but they are worn out so - I'm wondering if it would be ok to use the Michelin Pilot Sport 4 to replace the current set of tyres, the closest match with Pilot Sport 4 that I can find is a slightly lower profile at F 205/50/17 and R 235/45/17. Or if anyone has any reccomendations? Many thanks all! Joel Quote Link to comment Share on other sites More sharing options...
brillomaster Posted September 6, 2021 Report Share Posted September 6, 2021 (edited) 205/50/R17 is the standard size for the front on a 986, so that'll be fine. looks like MPS4 is available in 245/40/R17, so i'd go for that on the rear, only very slightly different to the standard 986 rear of 255/40/R17. Edited September 6, 2021 by brillomaster Quote Link to comment Share on other sites More sharing options...
joeluth Posted September 6, 2021 Author Report Share Posted September 6, 2021 (edited) 46 minutes ago, brillomaster said: 205/50/R17 is the standard size for the front on a 986, so that'll be fine. looks like MPS4 is available in 245/40/R17, so i'd go for that on the rear, only very slightly different to the standard 986 rear of 255/40/R17. Thanks @brillomaster Oh yeah , nice one you're right about the fronts! Not sure about 245/40 on the rear though, can I get away with that? standard 17 inch 986 boxster rears are 8.5 wide, but these 987 rear wheels are 8", the widest tyre on the chart is 235/50. Edited September 6, 2021 by joeluth Quote Link to comment Share on other sites More sharing options...
brillomaster Posted September 6, 2021 Report Share Posted September 6, 2021 actually, 235/45/R17 would be fine. you're right, that would fit better on an 8" rim, and its only 1.17% different to 255/40/R17, so well within generally accepted difference of +-2%. so yeah, 205/50/R17 front, 235/45/R17 rear. Quote Link to comment Share on other sites More sharing options...
½cwt Posted September 6, 2021 Report Share Posted September 6, 2021 235/45 will lengthen your gearing a small amount so will make your speedo read 1-2mph mph longer at 70 mph i.e. more than true speed. Quote Link to comment Share on other sites More sharing options...
½cwt Posted September 6, 2021 Report Share Posted September 6, 2021 31 minutes ago, ½cwt said: 235/45 will lengthen your gearing a small amount so will make your speedo read 1-2mph mph longer at 70 mph i.e. more than true speed. 235/45 will lengthen your gearing a small amount so will make your speedo read 1-2mph mph under at 70 mph i.e. less than true speed which will probably make it about spot on if you test it against a satnav or GPS speedo. Quote Link to comment Share on other sites More sharing options...
joeluth Posted September 6, 2021 Author Report Share Posted September 6, 2021 Thanks all, I think that settles it then, Pilot Sport 4 - 205/50/R17 front, 235/45/R17 rear, should be great! Finally getting my full geo setup tomorrow morning, I was hoping to get tyres beforehand but I spent forever reading reviews! no biggie though, I can fit them to a properly setup car later in the week. 1 hour ago, ½cwt said: 235/45 will lengthen your gearing a small amount so will make your speedo read 1-2mph mph under at 70 mph i.e. less than true speed which will probably make it about spot on if you test it against a satnav or GPS speedo. Thanks for the info, good to know, and one of the things on my list to sort is the discrepancy between the digi and the analogue speedo, the digi always seems to be reading a bit lower, I tend to just go by that. Quote Link to comment Share on other sites More sharing options...
Gwsinc Posted September 12, 2021 Report Share Posted September 12, 2021 Just had PS4s installed all round on my 2001 986, great tyre, probably the best out there for daily driving. Surprised to hear you couldn’t find 255/40/17 for the rear, I got some no problem from blackcircles. Quote Link to comment Share on other sites More sharing options...
joeluth Posted September 12, 2021 Author Report Share Posted September 12, 2021 27 minutes ago, Gwsinc said: Just had PS4s installed all round on my 2001 986, great tyre, probably the best out there for daily driving. Surprised to hear you couldn’t find 255/40/17 for the rear, I got some no problem from blackcircles. Mate I love my new pilot sport tyres, the old ones were ancient so anything would have been better but I'm very impressed with these, quiet, comfortable, crisp handling and really grippy. My wheels are off a 987 they are 8" wide at the back so I don't think I could have a 255/40/17... I went with 235/45/17 rears and I'm having an absolute blast in it! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.