Correct wheel offset for 986 cars
 

I searched a bit online and on here, and I cant really find a clear answer to this. I'd like to get a set of factory 18x8 and 18x10 hollow spoke turbo wheels for my 02 S. I am told that the 993 turbo wheels fit perfectly without spacers, while 996 wheels require a rear spacer. I am very against the use of spacers (mostly for convenience as I change wheels/ tires frequently and lug bolts are a PITA enough by themselves without gettingi spacers involved in the equation).

986 cars ideally want about 55ET front and 50ET rear, yes?

Any input from those who know would be greatly appreciated.

Patrick

Hi,

I recall when I was contemplating new rims and wheels last summer, from what I have read,...I don't recall if it was on this forum or PCA, but after 9.5, spacers are best to put on. This may be especially true if you have lowered your ride. I, too, didn't want spacers, but not for the reason that you described....anyway, I went w/ staggered rims (re: 8 X18 in the front and 9.5 X 18 for the rear). They haven't caused me any grief yet (knock on wood). :rolleyes:

Intererstingly, the Bentley Service Manual 1997-2004, p. 44-1 states that the approved tire combinations for 18 inch wheels are:

Front 7.5 X 18 (ET50) 225/40 ZR18
Rear 9 X 18 (ET52) 265/35 ZR 18

-OR-

Front 9X18 (ET52) 225/40 ZR18
Rear 10X18 (ET 65) 265/35 ZR 18

BTW, I am sure you know this, but our tool kit has an aluminum guide rod (re: threaded wheel centering stud) that you screw into the hub to make for an easier re-install of the wheels. If you don't have one, you might want to invest in one....I know Performance Products (I think that's the company) has them for something like 20 bucks. You may also want to check what our sponsors might have to offer.

Anyway, maybe some of the more knowledgeable guys out there can help out!

Good luck with your decision! :cheers:

I used to have 993 Turbo wheels on my Boxster. The rears were 18x10 w/ a 45mm offset,they fit perfectly with no problem. That is the biggest wheel size you can fit on a Boxster w/o spacers.

That looks correct, the 10x18 ET45 rear, vs what the Bentley manual states with the 65mm ET.

If the 993 Turbos are good thats what I'll be looking for.

Patrick

Just found a dandy chart on rennlist:

http://members.rennlist.com/911pcars/WheelWts.html

Apparently there were two versions of the 993 10x18 hollow spoke rears, one with a 40mm offset and one which is 65mm. Blinkwatt, do you know which version you used?

The fact that the Bentley manual suggests 65mm rear offset would mean you can use either the 65mm 993 turbo or the 996 turbo rears, which in that case would both be 18x10 at ET65.

So, for the 986 do we want 40 or 65 MM of rear offset?

Patrick

Per the Tequipment Boxster catalog it lists the 18x10 rears at et47 for both the Turbo look II and the SportTecho. The fronts are at 18x8 with et 50.

I spoke to the guys at HRE and they said for 986 Boxsters on a 18x10 wheel they like to see 40-50mm of offset, however I keep seeing the ET47 coming up more frequently, which leads me to believe that 47 is ideal, while 40-50 is acceptable. Either way, it seems 65 is out.

Patrick

Sport Classic 2
 

I have the sport classic 2 wheels on mine, and the chart says they are 65mm offset on the 10x18 wheel and 52mm on the 8x18 fronts.

But now to throw some coals in the fire, what is the largest tire size I can use in the front and the rear....really.

My 74 911 says 185 but I have a 205 on it. So for a boxster what is the widest tire i can put on my rim on the rear?

You should beable to go 275. I went 265 to be safe as I'm doing coilovers and didn't want to modify wheel wells once slammed. My rear et 56 w/ 10mm spacer. Fronts et 47 w/ 235x35x19 Rear tire size265x30x19 Hope this helps.

Just purchased a set of 993 Turbo hollow spokes, ET40 rear, so we'll see how these fit. They currently have Turbo size tires on (225/40-18F, 285/30-18R) so I should have some good input on how wide you can go once I get these on the car.

Patrick

I'm looking at a set of 996 TURBO wheels, would the offset fit my 00" S? The front seems to be fine but I'm worried about the rear, especially the 11" width?


Front 18x8 ET 50 with 225/40R18

Rear 18x11 ET 45 with 295/30R18

Thanks

Absolutely not. Short of doing fender flares, there is no way that you are going to fit an 11" wide wheel on a Boxster. By the way, as I used to have a set, the 993 Turbo Hollow Spokes come in either ET40 (Turbo or wide body fitment) or ET65 (narrow body fitment). I ran the 18x10 ET40 version, and while they fit, this is as wide as you can go. I am now running BBS RSII 18x10 ET45, and this is a perfect fit.

Thanks. Didn't think so neither. What size tyres are you running on those 18x10s?

How about 17" Offsets
 

I have a set of wheels (986 or 996 Twists...not sure):

17 x 7, 52mm offset (front) and
17 x 9, 55mm offset (rear)

with Toyo 888's. I used these on my 968. Will these work on my 2001 "S"?

Yup, those should work just fine. In my owners manual the standard offset for a 986 would be 50mm in front and 52mm in the rear.

Do you think this will fit my 986
 

i just got a 986 and i want to change my wheels,I found this on ebay do you think this set will fit my car

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290337637691&viewitem= &_trkparms=tab%3DWatching

Thanks

I have a 2000 Porsche Boxsterand one of these wheels will fit my car I found them on
 

wheel sizes: 19x8.5 front 19x11 rear offset 57 mm front 62 mm rear let me know if these will work on my 2000 boxer if they will work what size tires to put on dem front and back please help me out if these wheels don't fit recommend what size will fit the biggest fit front and back millimeter size with thank you I don't visit the the forms very much so e-mail me want some help bttybp071@aol.com

official Boxster wheel specs
 

Long dead thread resurrection?

Will They Fit?
 

seen a website that calculates wheel fitments, thought I'd share.

Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

I just picked up a set of Cayman wheels I want to put on the 986, they are 18s. Fronts are 8 with an ET57 and rears are 9s with ET43 I believe that is the numbers stamped on them. These are factory wheels so I would imagine they fit fine but anyone have any guesses as to how they will look? I couldn't pass up the deal, guy bought them for a 928 and they did not look good, he put new tires on them and drove a few blocks and they rubbed on the front, I got the wheels with $700 worth of tire on them for $400.

IN TERMS OF THE WIDEST WHEEL/TIRE SETUP FOR A PORSCHE BOXSTER 986 CHASIS...

INTRO:
For all-around performance and looks, go with 18x8.5" Front Wheel/Tire and 18x10.5" Rear Wheel/Tire setup. This 18" wheel/tire combination with good tires and suspension components amazingly allow the car to handle as if it's sitting on train-track rails! No spacers needed with this setup and they fill in the wheel well perfectly.

Hence, although 19" wheels work and look great, they don't perform as well, not even close. However, if you want to go with 19s and you're going to keep your car, I highly recommend that you replace all of your suspension components with race quality parts (from control arms to struts).

If you rub with either of the 18" or 19" setups I have mentioned, then you may own a car that has had front-end impact, and may require you to figure out what needs to be pulled out.

The positive aspect with going with a 19" setup is that your car ends up being a higher, which slightly helps reduce driveway/speed bump scrubs, until you need new tires.

CURRENT WHEEL DIMENSIONS (No Rub Issues):
:: Front: 19x8.5" (45 offset - 2" lip)
:: Rear: 19x10.5"****(43 offset - 4" lip)

CURRENT TIRE DIMENSIONS (No Rub Issues):
:: 
Front: 235/35/19 (25.48” Diameter)
:: Rear: 275/30/19 (25.49” Diameter)

FUTURE WHEEL DIMENSIONS (L+4" - R+4" Steel-Super-Wide-body Fabrication):
:: Front:19x9.5" (3" lip)
:: Rear: 19x13.5" (7" lip) +1" Spacers OR 1" Arm Extensions (alleviates spacers)

FUTURE TIRE DIMENSIONS (L+4" - R+4" Steel-Super-Wide-body Fabrication):
:: Front: 275/30/19 (25.5” Diameter)
:: Rear: 355/30/19 (27.4” Diameter)

THE SCIENCE BEHIND WIDER/STAGGERED WHEEL SETUPS:
In short, you typically want to stay within a 2" difference between the front and rear tires to avoid understeer/oversteer.

Based on this methodology, I should go with a 10" wheel up front; however, I would have to rework the entire steering and front end suspension system. And even then, for those who have driven a Viper with 10" wheels in the front and 13" i the rear, its challenging to turn. For cars that aren't setup for it, a similar wide-body setup would quickly wear-out relevant front and rear-end components.

Obviously, I am extending the fenders to accommodate the new wider wheels and tires; however, I sincerely do not recommend you doing what I am unless you have the funds to do it correctly (GT/RS specs).

Please be sure to also note that going larger and/or heavier will wear-out your bearings a lot quicker, but that goes for any sports car.

CONCLUSION
I truly hope this information helps one of you in some way. Such R&D knowledge doesn't come cheap and not many people I know or have ever met have produced such conversions unless they have large budgets to play around with. Personally, such R&D has cost me a few "million pennies" (so to speak), and what's left is pure knowledge, experience, and how to do things better each time around.

Best wishes,

MoMo
Self-taught Coach-builder/Industrial Engineer

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