987 Wheels on a 986?

[BoxMann]

As some of you know, I just bought a 2004 Boxster S. Mine has 17" wheels. A factory option was 18" wheels. So I've been thinking of upgrading and I've been looking around for 18" wheels. I just don't know which 18" wheels would fit, and which wouldn't. There's a guy very local who has a set of 18" wheels for sale from a 987, a 2007. Would these fit my 2004 Boxster S, without any needed modifications?

Does it matter whether it's a Boxster or a Cayman?

Does it matter whether it's 987.1 or 987.2?

What about 911 wheels if I find a set of those?

Speaking to the bigger issue, is there an easy, simple way for me to find out whether a particular set of wheels would or would not fit my 2004 S?

[MrBen]

Buy them and try to put them on

[BoxMann]

Originally Posted by MrBen

Buy them and try to put them on

I was hoping for a little more helpful, informative, knowledgeable, response than that.

[The Radium King]

try to put them on. if they fit then buy them.

[BrokenLinkage]

You might try to reach out to Johnny Danger via PM, as he is rather an expert on 986 wheel fitment. He is not very active on the forum these days, but can be very helpful when not tied up international spy scandals.

[JBauer]

Originally Posted by MrBen

Buy them and try to put them on

I did that �� , stressful. I put 19x8.5, 57 offset front and 19x9.5 on the rear of my 986. Don't remember the OS on rear. They fit no spacers. I bought new tires and will be getting them mounted next week and can find out the rear OS. Supposedly the will fit on Cayman or 911

[husker boxster]

Welcome to the world of offset - the amt of in & out a wheel sits on the hub. You need to pay attn to wheel width and offset when replacing OEM Porsche wheels. Thankfully, there are easy ways to figure out if potential wheels will work. The 1st item is knowing what a wheel's width and offset are. On Porsche wheels, they're stamped on the wheel right next to the valve stem. Then you take the current values and the potential wheel values and enter them in this offset calculator.

https://www.1010tires.com/Tools/Wheel-Offset-Calculator

It will tell you how far in or out the new wheels will sit on the hub vs the originals. Wheels that move too far inside may bump into suspension components, while too far out may bump fender lips.

Now to your specific situation...
Factory 986 18" wheels are 7.5" & 50mm Frt, 9" & 52mm Rear
Factory 987 18" wheels are 8" / 57mm F, 9" / 43mm R

You can adjust offsets with spacers. 5 or 10mm are common (my CSS came from the factory w/ 5mm spacers). You will need longer lug bolts if you use spacers. By eyeballing the above figures, the fronts will probably work w/o potential issues. The rears will probably need a 5 or 10mm spacer.

Chances are 911 wheels will not work, unless you want to go wild with massive spacers (the fronts probably would work but rears are too wide). Some forum members have made them work with 15mm spacers, but it's really not a good idea, esp if you want to do track days.

I have seen pics of 986s with 18" Cayman S wheels on them. Don't recall if spacers were required or not, but they will work. Search 'offset' for a lot of educational material.

[Dave80GTSi]

A perfect fit, with no fussin'

[linklaw]

I had a set of Cayman S 18" wheels on my 2001 Boxster S. They fit without spacers but did sit further out than the stock 18" 986 wheels.

[BoxMann]

Originally Posted by husker boxster

Welcome to the world of offset - the amt of in & out a wheel sits on the hub. You need to pay attn to wheel width and offset when replacing OEM Porsche wheels. Thankfully, there are easy ways to figure out if potential wheels will work. The 1st item is knowing what a wheel's width and offset are. On Porsche wheels, they're stamped on the wheel right next to the valve stem. Then you take the current values and the potential wheel values and enter them in this offset calculator.

https://www.1010tires.com/Tools/Wheel-Offset-Calculator

It will tell you how far in or out the new wheels will sit on the hub vs the originals. Wheels that move too far inside may bump into suspension components, while too far out may bump fender lips.

Now to your specific situation...
Factory 986 18" wheels are 7.5" & 50mm Frt, 9" & 52mm Rear
Factory 987 18" wheels are 8" / 57mm F, 9" / 43mm R

You can adjust offsets with spacers. 5 or 10mm are common (my CSS came from the factory w/ 5mm spacers). You will need longer lug bolts if you use spacers. By eyeballing the above figures, the fronts will probably work w/o potential issues. The rears will probably need a 5 or 10mm spacer.

Chances are 911 wheels will not work, unless you want to go wild with massive spacers (the fronts probably would work but rears are too wide). Some forum members have made them work with 15mm spacers, but it's really not a good idea, esp if you want to do track days.

I have seen pics of 986s with 18" Cayman S wheels on them. Don't recall if spacers were required or not, but they will work. Search 'offset' for a lot of educational material.

HB,

As usual, an excellent and thorough response and explanation. Thank you, sir.

[husker boxster]

Originally Posted by BoxMann

HB,

As usual, an excellent and thorough response and explanation. Thank you, sir.

You're welcome. It's not rocket science if you know the basics.

I should probably rephrase my comments on 911 wheels. The fronts generally work as the widths and offsets are similar between the 911 & Boxster. The rears aren't generally close. 911 rears can come in 10" and 11" variations. Both have a wild offset (I think 36mm IIRC). The offset is the reason 911 rear wheels are more difficult to use on a Boxster. People are always asking if the 11" rears will work on a Boxster. For a long time the pat answer was no, but a few members have somehow made it work. You just get into lots of hoop jumping to make it work. You're miles ahead by buying the 987 wheels and just slapping them on.

[BoxMann]

Originally Posted by husker boxster

You're welcome. It's not rocket science if you know the basics.

I should probably rephrase my comments on 911 wheels. The fronts generally work as the widths and offsets are similar between the 911 & Boxster. The rears aren't generally close. 911 rears can come in 10" and 11" variations. Both have a wild offset (I think 36mm IIRC). The offset is the reason 911 rear wheels are more difficult to use on a Boxster. People are always asking if the 11" rears will work on a Boxster. For a long time the pat answer was no, but a few members have somehow made it work. You just get into lots of hoop jumping to make it work. You're miles ahead by buying the 987 wheels and just slapping them on.

I understand the concept of offset -- distance from the centerline of the wheel to the mounting face -- just wasn't entirely sure how many mm's variation is tolerable, and how much isn't, and what exactly is done when the variation is too much. Also, don't fully understand how a variation in offset affects handling. Is it just a clearance issue?

Also, I understand that spacers increase offset, but how do you reduce offset if you're confronted with that? Like, the fronts on the 987 are 7mm more offset than current. Also, for example, what if in the 987 vs 986 the numbers on the rear were reversed where OEM was 43 mm and the wheels you wanted to install were 52 mm, or even, let's say, 57 mm?

And thank you for the further explanation on the 911 wheels.

[ripratama]

Originally Posted by BoxMann

There's a guy very local who has a set of 18" wheels for sale from a 987, a 2007. Would these fit my 2004 Boxster S, without any needed modifications?

Does it matter whether it's a Boxster or a Cayman?

Does it matter whether it's 987.1 or 987.2?

What about 911 wheels if I find a set of those?

Speaking to the bigger issue, is there an easy, simple way for me to find out whether a particular set of wheels would or would not fit my 2004 S?

Hi BoxMann,

From my experience in fitting 18" Boxster S II wheels from a 2011 987 to a 2004 986, I can confirm those will fit fine if you put correct tires i.e. 225/40 fronts and 265/35 rears.

The used wheels I purchased came with tires meant for 987 (235/40 fronts and 265/40 rears) which gave the 986 an ungainly taller look due to meatier sidewalls. I've since put on correct tires.

It shouldn't matter if the wheels come off from either the 987 Boxster or Cayman.

Husker Boxster has summed it up just right regarding 911 wheels. Their lower offset and wider width will be challenging to fit.

Do note that a lower offset number (eg. 35 mm against 50 mm) will position the wheel 15mm more outward if the width is identical. Wider wheels mean even more protrusion coming outward. You may need to roll fenders or adjust the camber to fit the wheels nicely. Some people take risk in "shaving" their inner wheel hub to increase the offset by few mm.

Higher offset numbers can be countered by fitting spacers, e.g. fitting 10mm spacer to a 50mm-offset wheel to achieve 40mm final offset.

The only sure way to know if a specific wheel set fit (or doesn't fit) a car is to try them on and turn the steering wheel to its extremities, and check for any physical contact. You should also drive over speed bumps to sense any rubbing. In any case, the outer diameter difference between old and new tires should be kept less than 5%.

[BoxMann]

As it turns out, the local guy with a "set" of OEM wheels from a 2007 didn't have a "set", he just had four wheels, all front wheels. So that deal is off. But I'll keep looking.

And thank you Rip for the additional info.

[rjh986]

If you can wait a month, the Hershey Swap meet always has a boatload of wheels and whatnot.

https://www.pca.org/event/2019-01-31/porsche-only-swap-meet-hershey-pa

[BoxMann]

Originally Posted by rjh986

If you can wait a month, the Hershey Swap meet always has a boatload of wheels and whatnot.

https://www.pca.org/event/2019-01-31/porsche-only-swap-meet-hershey-pa

Thanks RJH. I was not aware of that event.

Also -- looks like we have the same car !

[rjh986]

I went the last 2 years and a few other times in the past. It's a nice drive and an excuse to get to know your new car. More p-cars in one spot than you even have seen and nice to walk around and check things out. You have to do it at least once!

[BoxMann]

Originally Posted by Dave80GTSi

A perfect fit, with no fussin'

Two questions:

1) Did you use a 10 mm spacer on the rear?

2) Was it a noticeable boost in handling, more precise turn-in, etc going from 17" to 18"?

[Dave80GTSi]

Originally Posted by BoxMann

Two questions:

1) Did you use a 10 mm spacer on the rear?

2) Was it a noticeable boost in handling, more precise turn-in, etc going from 17" to 18"?

Nope, no spacers required. I would have mentioned it should that have been the case.

Yes, turn-in does seem a slight bit "quicker" than before. In my view, not really a big deal for a street car.

What you will most notice, though, is how much better the wider wheels fill out the wheel wells visually, especially the rears.

[BoxMann]

Hmmm . . . so turn-in and handling only slightly better? If I made the change to 18", it would be for performance/handling, not for cosmetics. I don't track mine, just street. Sounds like you're saying it's not much of a performance/handling/cornering difference.