Please confirm Wheel and Tire Upgrade sizes
 

I've done numerous searches on here, but not found 100% confirmation of what I'm doing with upgraded wheels and tires. Hopefully someone can clarify/confirm I'm ok on this.

I have a '99 Base Boxster with factory 17" wheels. I just bought a set of used 18" wheels from a 2007 Boxster S. These wheels are shown as:

F = 18x8J ET57
R = 18x9J ET43

I looked on TireRack and they recommend this exact spec for my Boxster as optional wheels, and recommended tires as:

F = 225/40ZR18
R = 265/35ZR18

I'm trying to make sure these are going to fit without any rubbing or use of spacers, etc., and not 100% sure how to be sure. I'm relying on TireRack being correct in their recommendation, but thought before I head to the tire shop to get them installed, I would double check here to be sure I'm okay on this.

Thanks in advance for any help!

I think they are exactly what I put on my 986S. The new ones are from a Cayman S and the fit fine. Ideally I’ll fit spacers at the front but the rears are perfect. Fronts would benefit from pushing them out a little further but everything clears fine.

I would think the car is over tyred with these sizes but for regular road use it’s perfect. For track I’ll revert to the 17” rims as I think it will be more fun.

https://uploads.tapatalk-cdn.com/201...2752547425.jpghttps://uploads.tapatalk-cdn.com/201...392cb613f6.jpghttps://uploads.tapatalk-cdn.com/201...e65d854257.jpg


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Those are the standard 18" Boxster tire sizes, and lots of folks have run the 18" Cayman S wheels on their 986 boxsters, which have those same widths and offsets. Some run a 5-7mm spacer in the front for looks with that combo, but I don't think it is required. Search for "Wheel" threads or for folks that are running the 18" Cayman S wheels to get a confirmation from someone that is running that size. In fact I think someone on here recently got a set of 18" 987 wheels and is successfully running them.

Edit: looks like the other forum member I was thinking about has posted to the thread with pictures :)

WOW! THANKS! Yes, exactly same wheels! And I just picked up red caliper paint to redo my black calipers, so will have the same look! Thanks for posting the pictures. Exactly the look I'm going for. Mine is black, but yours is close enough to make me feel pretty darned glad I bought the wheels. And no racing (old timer), just street use here in SoCal.

Thanks again!

No worries Neil, I had checked all measurements etc and the fronts were the concern. The fit perfect with no rubbing or clearance issues but as Steve mentioned they would look better with a spacer on the front. The outside tyre profile is exactly where the 17” was (20mm inside body work) so pushing them out would help the look.

Rears look perfect standard in my opinion.

Oddly I think the ride improved on the 18” but I suspect that’s the better tyres as my fronts were ancient and the rears were a Chinese ditch finder brand that the previous owner put on just before I bought it.


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Got the new wheels installed and really like them! Also went with a different tire, the General G-MAX AS05. I like the new tires much better as well. Looks like everything fits fine. No problems reported as I watched the shop install them. Now I just need to paint my calipers red!

Next project: new top with glass window!

http://986forum.com/forums/uploads02...1509733515.jpg

Another pichttp://986forum.com/forums/uploads02...1509733774.jpg

Looks great!!


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I put the twist wheels on 18's

Has anyone gone in the opposite direction ?
I mean fitting 17" rims to a Boxster S to use higher Aspect Ratio tires to improve the ride? Before you snigger - it may help with resistance to wheel damage from potholes and may allow snow chains to clear.
This may help some people justify keeping their old 17" rims or boost their value if sold to support the 18" upgrade.
Thanks.

I am running 17" Boxster S wheels on my base Boxster with S front brakes OFF Track, there is no clearance issue. I run the Cayman S wheels or Allgerita's 8"-F 9"-R on track I have no body clearance problems in either set even with the car lower 1.5" or more I do use spacers on track 17mm front and 7 mm rear. The spacers are only used to help with my high negative chamber on track.





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Hi all. I have a 2003 Boxster with 16" wheels (why would you? ) and I want to go to 17" wheels. Will this effect the speedo reading and if so can it be re programmed Present tyres 205/55 - 16 front and 225/50 - 16 rear. Want to fit 205/50 - 17 front and 255/40 - 17 rear. Thanks Dave

go here --https://tiresize.com/speedometer-calibration/

All you need to do is go with tires that have virtually the same diameter. Look at tire specs and you will see diameter as one of the listed items

I think 255/40/17 is comparable to 225/50/16. I use 255/40/17 for summer and 225/45/17 snow for winter. Speedo deviation should be insignificant.

You can go 225/45/17 up front on factory 17x7 rims.