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997 GT3 Tyre Advice

-ollie-

Well-known member
Joined
26 Sep 2018
Messages
157
Hi Guys,

New member here, just posted in the "noob" section to say hi :bye:

I've a 997.1 GT3 CS that I'm doing a few trackdays in. I'm new to Porsches, but not new to TD's and also circuit race an E36 M3.

My car is currently on OEM 19's, with Michelin Pilot Sports.

I plan to fit some Cup 2's before my next TD in a couple of weeks. I'd like to know what the maximum width you guys have run front & rear on OEM wheels is. I'm tempted to fit;

255/35/19 front
325/30/19 rear

Has anyone else done this? A Pilot Sport looks a little stretched to me with a 305 on a 12J, and I think the front end would benefit from a slightly wider tyre.

Can anyone point me in the right direction of the best (most competitive) source of Cup's? I'm not accustomed to buying such large tyres - yet!

Thanks in advance.

Ollie
 
There are many suppliers who may have promotions on at different times so always worth checking a few, but in general Camskill are hard to beat on price for straight forward mail order and Blackcircles are a good combination of decent price along with making it easy to book fitting at a place that's convenient in the same transaction.
 
MJA911 said:
There are many suppliers who may have promotions on at different times so always worth checking a few, but in general Camskill are hard to beat on price for straight forward mail order and Blackcircles are a good combination of decent price along with making it easy to book fitting at a place that's convenient in the same transaction.

Spot on, thank you. I'll check both of those out.

Do you have any experience of "super sizing" tyre sizes, particularly on the front?
 
I liked the standard tyre widths on my GT3 aethetically plus I tend to stick with factory settings so I don't have supersizing experience, but I have seen discussion on here about slightly wider front tyres as well as geometry and arb settings (more negative camber and softer arb settings at the front/stiffer at the rear) to increase front end grip.

By the way, welcome to the forum, invaluable experience and expertise on here, opportunities to meet up sometimes too. Great choice of car, had fun in mine, amazing machine on a track, yours being a CS even more so :thumb:
 
255 probably won't fit the front. 245 should but you may need extra camber, what's it set to? 305 on the rear, 325 will probably rub. 305 is stretched as it's a 12" rim but it's also spaced 5mm from the factory. Either way that's plenty of tyre. It will understeer when pushed on a std geo regardless.

I would go 245 f, 305 r, then get it set up with more camber both ends.

Welcome to the forum.
 
Appreciate the input guys, have just found a good deal on some new Cups in OEM size so they're on order.

Also dropped Chris @ CG a note asking for a slot to get a geo done. No idea what the settings are at the moment!
 
-ollie- said:
Appreciate the input guys, have just found a good deal on some new Cups in OEM size so they're on order.

Also dropped Chris @ CG a note asking for a slot to get a geo done. No idea what the settings are at the moment!

FWIW, I think you've done the right thing. If you have decent tyres and a good set up, you're soon in the zone.
 
Amongst many things it taught me, my GT3 responded to geo settings more than the regular 911's I've had, there's more that can be adjusted of course. Factory settings were fine for all rounder (camber -1'30", standard arb and ride height) and with less camber, softer arbs, top of ride height range it was nicer on the road, but not surprisingly would understeer on the track. Set lower, with at least -2' camber, stiffer arbs etc., it made a big difference plus with an instructor shouting in my ear I could avoid understeer by driving it properly :oops:

CG know all this inside out of course and will personalise it for you.
 

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