Wheel offsets

[sawood12]

Anyone know what the offsets are on the 17" Boxster 5 twist spoke wheels? I got a set not long after I bought my car and fitted them staight away. I've had no problems with tramlining or any other handling-type issues but I have recently read that on 944's you should fit the front ones with 7mm spacer. The original wheels on my car were the 16" Teledials.

I cannot read the figures that are either side of my valve as the wheel refurbishers were a bit too vigarous when they were cleaning up the wheels and have made the numbers illegible.

 

[Guest]

have a look at the pretty pictures here: http://www.911pcar.com/Porsche_Parts/porsche_parts_wheels_911.htm

they list the offsets too.

 

[A5DSR]

Are they like mine, 996/Boxster wheels. These are 7 55 front & 9 55 rear.
I have 968 castor mounts and it still tramlines. I'm thinking of trying 7mm spacers at the front but not sure if there'll be enough thread length.

 

[Fen]

It's unlikely that spacing the wheels further out will reduce tramlining, I imagine. It's weird that you get much though; my Cup1's are 7" ET55 and I don't get any. Is the alignment all within spec? Was it set with the Boxster wheels fitted?

 

[John Sims]

I have Boxster/993 wheels on Beaky and found that he would tramline like a sod, even with 968 mounts. He doesn't now having replaced the top mounts with spherical bearing ones from Simon at ESS.

It is reckoned that you should have 7mm spacers at the front, but I haven't done mine yet as I feel it would be prudent to fit longer studs.

I agree with Fen that spacers shouldn't have much bearing on tramlining, but they should improve turn in and reduce understeer.

 

[sawood12]

My wheels are the same as the ones pictured above. Luckily I never had a tramlining problem before and still don't and i've fitted 968 castor mounts which also had no affect on tramlining so I guess I must be one of the lucky ones!

I can get the offset from Mikes link assuming that this design of wheel only came in one offset value for a given wheel width. You seem to be able to get different offsets for the Cup 3 5-spoke twists. So I assume that the difference between the offsets on my Teledials and these wheels should give me the width of the spacer as both wheels are the same width.

John - does the top mount replacement you mention mean replacing the whole of the rubber top of the McPhearson strut?

 

[John Sims]

ORIGINAL: sawood12

....John - does the top mount replacement you mention mean replacing the whole of the rubber top of the McPhearson strut?

Yes. See http://www.klaindustries.net/strtmnt/strtmnt.htm

Simon's strut braces also come from KLA Industries which is how he got the top mounts I guess. There is a small amount of movement on the bearing which can produce a knock but this could be removed with shimming (if I could be bothered). On the whole they are very cheap but do a good job. Get some!

 

[Diver944]

How much tread do your front tyres have? I'll tell you why?

When I first fitted 17" wheels I had a bit of tramlining. I duly changed to the 968 caster mounts and had an alignment which made it better but not perfect. The 17" wheels were S/H and came with very worn front tyres (225/45) but brand new rears (255/40). In a fit of pique I experimented by fitting the rear wheels on the front with the massive 255 tyres. Amazingly the tramlining was much reduced, even with 255s??[&:] I quickly changed them back though - looked odd []

When the fronts eventually wore out I replaced them with brand new ones and voila the tramiling was again vastly reduced.

My personal theory is that worn fronts provide much more grip on a dry road due to the lack of tread block movement, and so you get more tramlining. New tyres with lots of tread are more compliant and resist tramlining.

Of course you will now post that your fronts are brand new [8|]

 

[A5DSR]

The front tyres were off the Boxster and have about 4mm left.
I'll try putting the teledials back on the front see how it feels then. If this is ok then I'll get a new pair of boots for the front.

Thanks

 

[John Sims]

You could we be right on the new tyres Paul as Beaky has had new tyres around the same time as his top mounts.

Another thing to consider is all cars wear their tyres differently so a second hand set could be worn in such a way as they track differently on the current car - the degradation may not be apparent when looking at the tyre.

 

[A5DSR]

Just out of interest, what size tyres do we have on the front?

 

[John Sims]

ORIGINAL: A5DSR

Just out of interest, what size tyres do we have on the front?

Well A5.. , I'm not sure what you've got [] but I've got 215's .

 

[Diver944]

I did have 225s on my old Cup wheels, but on the current Boxster twists I have 205s

 

[944turboS]

Paul
The later 2.7 wheels should be a straight swap.

The Boxster wheels will if I understand this correctly need 6mm spacers at the front (smallest available) & 15mm at the rear.

 

[Fen]

I'm going to completely disagree I'm afraid.

For your wheels, Paul, the later ones won't fit if they are circa 52 offset as that is a post'87 dimension and your car is an '86 which uses the earlier circa 23mm offset. You will need 30mm spacers to make them fit.

The Boxster wheels should be a straight swap for the other chap - there is no point worrying about 2.3mm. It's in danger of looking very tucked under the arch going from a 7" down to a 6" wheel and he may want to use a 15mm spacer for cosmetic reasons.

 

[944turboS]

Thanks Fen I had the difference made by increasing the off set the wrong way round, having looked up one of your previous posts ( http://www.porscheclubgbforum.com/tm.asp?m=182925&mpage=2&key=offset&#188258 ) I now know my initial response was incorrect.

 

[Fen]

Leaving aside that you already have the best wheels that will fit IMO, you'd need ET of around 23 or so in any other wheels you wanted to use.

 

[Fen]

That's close enough to work.

 

[944 man]

It wont work George. The 951 Fuchs differed from most other 7" x 16" (but actually not all) by having more backsapce, in order to accomodate the brake calipers.

You could mix these wheels with 86MY wishbones, hubs and calipers and M030 dampers, but theres no room for radially mounted calipers and ABS is a non-starter too, sorry.

 

[Lowtimer]

Nit-picking slightly, the late TurboD90 wheels are 7.5" front and 9" rear, not 8" and 9".

However, if you prefer slightly narrower wheels and tyres on a late Turbo, as I do for overall road use, just bung a set of S2 wheels on: i.e. 7" and 8" D90s, late offset, using 205/55 16 front tyres and 225/50 16 rears. That's what I am running on mine for everyday wear, and it's lovely. S2 wheels look pretty standard on the car, and enable it to be a bit more light-footed and delicate. I have about 300 bhp and a limited slip diff in good working order and have always felt the car has excellent traction. In deference to the drive shafts and UJs I don't habitually use full everything in bottom gear but can use full waft in second in even quite poor weather. Another advantage of S2 sizes is that there's a wide choice of available tyres in the split S2 sizes than for the late Turbo rears with their unusual 245/45 16 section.