V

hi guys!

Did a bit of research and I still have a few questions unanswered. I am contemplating building a set of GT2 wheels using the 993 RS speedlines as a base for this. What I need to know is:

1. Can someone confirm these specs of the 993 GT2 Wheels:

Front: 9x18 ET34
Rear: 11x18 ET18

2. More importantly: How deep are the front and rear outer rim halves?

My guess: Front: around 2,5" outers Rear: around 4" outers

3. For those of you who have the 993 RS speedlines, is figure "C" in the diagram below different when you compare the front wheel centre and the rear wheel centre? E.g Are the centers identical as far as caliper clearance or do any of the centres allow for more caliper clearance than the other? According to my calculations (taking total wheel width and ET into consideration) it seems from a theoretical viewpoint that the front wheelcentre would have a bit less caliper clearance than the rear wheel centre. I might be mistaken though..

Hopefully with some help I will be able to do this. If someone on here have OEM GT2 wheels that that would be perfect. Graeme where are you?? Toby, Jean, clubsport1, anyone??

Thanks guys.

TB993tt

Can confirm item 1 is correct - don't have any Speedlines anymore (got stolen) so can't help you with the rest.....

TB993tt

Just read what you wrote on the 993 Forum - Graeme's GT2 will have the 9X18ET34 up front, it is not an "EVO", they were the race cars of the era.

V

Thanks Toby. What are the specs. of the BBS wheels you have now? You had the original GT2 magnesium wheels before, right? Bill V stated a 11x18 ET14 for the rears, while yours were ET18?
What tires are you running? TIA

TB993tt

My BBS race wheels are exactly same offsets as GT2 Speedlines 9X18ET34 11X18ET18
Bill V is describing some race wheel sizing application I guess - the extra 4mm on the 11X18ET14 will fill the stock GT2 arch better. I though most racers ended up with 12" wide rears or more....
I run stock 993tt tyre sizes...

jim dorociak

Viggo, TB993tt is saying what I did in my last email to you. Why stop at 11" I am sure 12" can be made simply by adding to the inside and still have plenty of outside lip. Tire wise I think you quickly get to the 315/30/18 or even the 330/30/18 sizes. You guys have enough horsepower that probably needs extra grip anyway.
Jim

V

Toby and Jim, thx for your responses. I hear ya Jim, 12" works as well . Toby, are your arches just as wide as the GT2 ones? Are you using spacers with your BBS wheels or do they bolt directly onto the hub? Is it a tight fit in the rear?

TB993tt

Different arches, look here:
https://rennlist.com/forums/993-turbo-forum/422999-aerodynamic-musings.html

No spacers, arches were installed to fit these wheels with an intentional "tight fit" for aesthetic reasons

Geoffrey

The BBS race wheel center will differ depending on the usage. If you have the 380mm endurance brakes, then you need a wheel center to clear the calipers. The race cars of that era used mag centers with a part number of 8039 front and 8051 rear and will clear said calipers. From there you can order the wheel halves in 1/2" increments. Since BBS has transitioned to the Aluminum center, they can provide an aluminum center in the same offset as the mag 8039 and 8051.