tire size for 993TT

porschemeister · 01-25-2008, 04:03 PM

I am in the finishing stages of my GT2 conversion and I am trying to decide which tires and sizes to use.

My wheels are 9x18 in the front and 11x18 in the rear.

The original sizes were 235/40 in the front and 285/35 in the rear.

Can't get MPSC's (my first choice) for the rear in that size. The rear tires are only available in 285/30 or 295/30 with a diameter of 25.1 and 25.2 inch respectively.

The front diameter is 25.7 for the 235's which I would like to stick with.

What to do about the rear? Go to a 315/30 with a diameter of 25.5 which would work with the front or go to a different tire altogether (Hoosier etc.)?

Any input greatly appreciated

cytefx · 01-25-2008, 04:09 PM

i think some have gone to a 305 rear, can you get that in that brand?

Bradford · 01-25-2008, 04:27 PM

It would seem that with the GT2 flares you would want to fill the flare with as much tire as possible depending on the wheel offset. I would go with the 315's on the rear and match the diameter with 235/245 in front.

How about some updated pictures of your car?

canysmc · 01-25-2008, 04:59 PM

Some here have gone 245/315

But wheel widths and offsets are critical for fitment

Check with member AndyT

JJayB · 01-25-2008, 05:22 PM

Jochen,
I ran 315's with no trouble on 11's. I wouldn't go more than a 263/35/18 in front with a 9'' if you have the right offset. I get a little tire rub on the inside with 245/40/18 Hoosier's on 9" rims if I turn the front wheels to right or left lock. With GT2 fender flares you should be ok. If you want to be safe you can run the 235/40/18. Diameter should't be a problem as the 315, 265 and 235 are all within 1/10 of an inch.

Jimmy

tar6day · 01-25-2008, 08:55 PM

265/35/18 front on 9" rims. 315/30/18 rear on 11" rims. MPSC's. No GT2 fender flares.

Jean · 01-26-2008, 01:35 PM

Hi Jochen, looking forward to see the final product impatiently!

As far as tires, you have many choices depending on your usage. I know this will be your fun street/track car, so I am guessing a set of R Compounds but also maybe a set of good street tires.

The GT2 had the taller diameter (circa 26") with the 285/35s, it was a great choice as it gave enough tire contact area while keeping the width within reasonable limits to support decent gas mileage through taller gearing and less transmission wear through going taller rather than wider. As you know a taller tire will give you equivalent larger contact area similar to a wider one (say 295s).

I am assuming you are running an LSD with your 2WD conversion, so in street tires, a good combo would be :

Michelin PS2:
Fr 245/40 --25.7"
Rr 295/35 --26.1"

You need to be careful with your fender flares, I know TB993TT had issues fitting the taller 295/35 tire in his car despite the flares, since they were fitted too tightly.
Yoko Advan Sport:
Same sizes as above. The 295/35 in N0 (Porsche) rating are heavy though relative to others.

In R Compound tires for aggressive track driving and streetable overall with decent life;
Sport Cup:
Fr: 265/35
Rr: 315/30

For aggressive track without caring much about highway/street driving:
Hoosier R6:

Fr 275/35
Rr 335/30
The above gives excellent neutral handling for 2WD with a properly setup car, but is full track.

My favourite is the MPSC setup above for street and track, like Tar6day as well. The Hoosier are fantastic in these sizes but too heavily biased towards track. The 265 up front still gave a decent (light)steering feel with the 2WD combo.

The set of Michelin Cup slicks that I have are 27" tall so they are substantially taller than any of the above, some GT2 race cars used even 28" as you know, there is still a bit that we are leaving on the table.

Cheers

porschemeister · 01-26-2008, 03:07 PM

WOW!

Thanks to you all that is really great information and will make it much easier for me.

Since I have 2 sets of Speedlines (Jean thanks again!) I think I will do two different set ups.

One for the street with either PS2's or MPSC's and the other with Hoosiers.

That way I have the best of both worlds! Thanks again to everybody for their informative input.

I will see the car in a week or 2 and will post pics. It's coming along really nicely (albeit slow...) thanks to Dieter who is in my opinion one of the best out there!

I had him install the Bilstein fully adjustable GT2 shock absorbers in combination with 900 lbs front and 1000 lbs springs rear Eibach springs.

Swaybars are factory 23mm (5way) in the front and 20mm (3way) in the rear.

I have a Matter half cage and I am still debating if I should weld a crossbar to it for the harness (it did not come with one!) or mount the harnesses on the rear shelf. Any input appreciated.

Can't wait to drive the beast, it wil be my dream car coming true

porschemeister · 01-29-2008, 08:49 PM

Car coming together! Enjoy the pics

WHB Porsche · 01-29-2008, 09:17 PM

Lookin' good! Are those the factory Speedlines or the Techart "copies?"

It really does look mean. I can't wait 'til it's done.

jmayzurk · 01-29-2008, 10:12 PM

Quote:

Originally Posted by porschemeister

I am in the finishing stages of my GT2 conversion and I am trying to decide which tires and sizes to use.

My wheels are 9x18 in the front and 11x18 in the rear.

The original sizes were 235/40 in the front and 285/35 in the rear.

What to do about the rear? Go to a 315/30 with a diameter of 25.5 which would work with the front or go to a different tire altogether (Hoosier etc.)?

I am running 315/30-18 Michelin PS2 on an 11" wheel on my 2WD 993TT with stock bodywork. This seems like a good choice since it's the factory 996GT2 size, so tires should be more readily available.

porschemeister · 01-29-2008, 11:59 PM

they are the real Speedlines. I got one set from Jean and had another set built by Speedline.

Decided to go the MPSC route and now I am told no 315's available....

Full Boost · 01-30-2008, 01:03 AM

OMG!!!

I am in love...... Thats what my car wants to be when she grows up!!!!

And Black too!!!! Ohhh my....

Simon.

chris walrod · 01-30-2008, 01:10 AM

Quote:

Originally Posted by Boost Crazy

OMG!!!

I am in love...... Thats what my car wants to be when she grows up!!!!

And Black too!!!! Ohhh my....

Simon.

Amen to that! What an awesome car! Always wanted to do a GT2 look (and go, for that matter) -- Cant wait to see more images!!

AndyT · 01-30-2008, 08:30 AM

i ran 245 and 315s on 9s and 11.5s. You can run 265s up front but will encounter some fender liner rubbing. Looking Good buddy ! I wanted to se my old hood on there : )

01-25-2008, 04:03 PM	#1
porschemeister Addict Rennlist Member Join Date: Aug 2005 Location: CA East Bay Posts: 172	tire size for 993TT I am in the finishing stages of my GT2 conversion and I am trying to decide which tires and sizes to use. My wheels are 9x18 in the front and 11x18 in the rear. The original sizes were 235/40 in the front and 285/35 in the rear. Can't get MPSC's (my first choice) for the rear in that size. The rear tires are only available in 285/30 or 295/30 with a diameter of 25.1 and 25.2 inch respectively. The front diameter is 25.7 for the 235's which I would like to stick with. What to do about the rear? Go to a 315/30 with a diameter of 25.5 which would work with the front or go to a different tire altogether (Hoosier etc.)? Any input greatly appreciated

01-25-2008, 04:27 PM	#3
Bradford Addict Rennlist Member Join Date: Mar 2004 Location: Westlake Village, Ca. Posts: 909	It would seem that with the GT2 flares you would want to fill the flare with as much tire as possible depending on the wheel offset. I would go with the 315's on the rear and match the diameter with 235/245 in front. How about some updated pictures of your car? __________________ Scott 96' 993TT 3.8

01-25-2008, 04:59 PM	#4
canysmc Addict Rennlist Member Join Date: May 2004 Posts: 2,744	Some here have gone 245/315 But wheel widths and offsets are critical for fitment Check with member AndyT __________________ canysmc 1996 Porsche 993tt 2006 BMW M5 2006 BMW 750Li 2007 Mini Cooper S Vert Sparkling Silver/Malt Brown/Sidewalk Before: 1971 911 1985 911 1987 930 1985 535i 1987 535is 2001 M5

01-25-2008, 05:22 PM	#5
JJayB Addict Rennlist Member Join Date: Jul 2001 Location: Orange Park Acres, CA Posts: 918	Jochen, I ran 315's with no trouble on 11's. I wouldn't go more than a 263/35/18 in front with a 9'' if you have the right offset. I get a little tire rub on the inside with 245/40/18 Hoosier's on 9" rims if I turn the front wheels to right or left lock. With GT2 fender flares you should be ok. If you want to be safe you can run the 235/40/18. Diameter should't be a problem as the 315, 265 and 235 are all within 1/10 of an inch. Jimmy __________________ Jimmy 993tt ANDIAL 3.8 twin plug (sold) 08' CLK 63 Black

01-25-2008, 08:55 PM	#6
tar6day Addict Rennlist Member Join Date: Jan 2004 Location: ohio Posts: 548	265/35/18 front on 9" rims. 315/30/18 rear on 11" rims. MPSC's. No GT2 fender flares. __________________ Tim 2008 GT3 RS Signal Green 2008 Subaru WRX STI Super Production class Rally America 2005 F-350 SD 6.0 Liter Diesel DRW (vinyl matte black, 22.5's and a single stack) 1997 993 TT Arena Red/Black (sold and missed!) 1997 993 RSR 3.8 (sold and missed!) 2004 24ft Haulmark Edge (sold)

01-25-2008, 04:09 PM	#2
cytefx User Join Date: Aug 2007 Location: uk Posts: 133	i think some have gone to a 305 rear, can you get that in that brand?

01-26-2008, 01:35 PM	#7
Jean Addict Lifetime Rennlist Member Join Date: Apr 2002 Location: Dubai- Beirut Posts: 4,490	Hi Jochen, looking forward to see the final product impatiently! As far as tires, you have many choices depending on your usage. I know this will be your fun street/track car, so I am guessing a set of R Compounds but also maybe a set of good street tires. The GT2 had the taller diameter (circa 26") with the 285/35s, it was a great choice as it gave enough tire contact area while keeping the width within reasonable limits to support decent gas mileage through taller gearing and less transmission wear through going taller rather than wider. As you know a taller tire will give you equivalent larger contact area similar to a wider one (say 295s). I am assuming you are running an LSD with your 2WD conversion, so in street tires, a good combo would be : Michelin PS2: Fr 245/40 --25.7" Rr 295/35 --26.1" You need to be careful with your fender flares, I know TB993TT had issues fitting the taller 295/35 tire in his car despite the flares, since they were fitted too tightly. Yoko Advan Sport: Same sizes as above. The 295/35 in N0 (Porsche) rating are heavy though relative to others. In R Compound tires for aggressive track driving and streetable overall with decent life; Sport Cup: Fr: 265/35 Rr: 315/30 For aggressive track without caring much about highway/street driving: Hoosier R6: Fr 275/35 Rr 335/30 The above gives excellent neutral handling for 2WD with a properly setup car, but is full track. My favourite is the MPSC setup above for street and track, like Tar6day as well. The Hoosier are fantastic in these sizes but too heavily biased towards track. The 265 up front still gave a decent (light)steering feel with the 2WD combo. The set of Michelin Cup slicks that I have are 27" tall so they are substantially taller than any of the above, some GT2 race cars used even 28" as you know, there is still a bit that we are leaving on the table. Cheers __________________ Protomotive 993 3.8TT 2WD. 100-200kph -> 5.2s @1Bar

01-26-2008, 03:07 PM	#8
porschemeister Addict Rennlist Member Join Date: Aug 2005 Location: CA East Bay Posts: 172	WOW! Thanks to you all that is really great information and will make it much easier for me. Since I have 2 sets of Speedlines (Jean thanks again!) I think I will do two different set ups. One for the street with either PS2's or MPSC's and the other with Hoosiers. That way I have the best of both worlds! Thanks again to everybody for their informative input. I will see the car in a week or 2 and will post pics. It's coming along really nicely (albeit slow...) thanks to Dieter who is in my opinion one of the best out there! I had him install the Bilstein fully adjustable GT2 shock absorbers in combination with 900 lbs front and 1000 lbs springs rear Eibach springs. Swaybars are factory 23mm (5way) in the front and 20mm (3way) in the rear. I have a Matter half cage and I am still debating if I should weld a crossbar to it for the harness (it did not come with one!) or mount the harnesses on the rear shelf. Any input appreciated. Can't wait to drive the beast, it wil be my dream car coming true

01-29-2008, 09:17 PM	#10
WHB Porsche I'm Still Jenny Rennlist Member Join Date: May 2006 Location: Somewhwere between Boston and DC... Posts: 4,635	Lookin' good! Are those the factory Speedlines or the Techart "copies?" It really does look mean. I can't wait 'til it's done. __________________ Charlie B. Last edited by WHB Porsche; 01-29-2008 at 10:14 PM.

01-30-2008, 01:03 AM	#13
Full Boost Addict Rennlist Member Join Date: Sep 2004 Posts: 1,235	OMG!!! I am in love...... Thats what my car wants to be when she grows up!!!! And Black too!!!! Ohhh my.... Simon. __________________ Simon. "There is NO such thing as OVERTRAINING. If you're overtrained, it means that you didn't train hard enough to handle that level of training…... So you weren't overtrained; you were actually undertrained to begin with…... MORAL = The guy who trains the hardest, the most, wins."

01-30-2008, 08:30 AM	#15
AndyT Addict Rennlist Member Join Date: Aug 2004 Location: NJ Posts: 1,425	i ran 245 and 315s on 9s and 11.5s. You can run 265s up front but will encounter some fender liner rubbing. Looking Good buddy ! I wanted to se my old hood on there : ) __________________ 2000 GT3 Cup Car, Becker VIP#1: (SOLD) 1997 993 TT (SOLD) Thanks to: http://www.reiser-technik.com/ http://www.ultimategarage.com/ http://vbdgraphics.com/ http://www.emersonautobody.com/]