Al Pettee

Question for all the 993TT experts here: What kind of tire sizes can we go with front and back on the 993TT without running into rubbing issues?

I have my stock 996TSCab rims on my 993TT (18X8.5" in front/18X11" in the rear) which is finishing up its tuning with Protosport in New Jersey, and since I'll be running around 600/650 lb-ft/HP, I am interested in maximizing rubber for extra traction. Right now I have Michelin PS2's on (225/40-18 on 8.5" up front and 295/30-18 on 11" in the rear) and for street driving, I was wondering if I could get the 235/40-18 PS2's on in front and 315/30-18 in the rear?

Protosport installed the H&R Clubsport suspension which also could affect fitting. I'll also give them a call Monday with this question, but would be interested in others' experiences/opinions.

Al Pettee

I did a search on Tire Rack and noticed that the Kumho Ecsta V700 tires are available in 225/40-18 and 305/30-18 sizes. I wonder if this combo. could work on the 993TT. Here is a comparison of the PS2's (current setup and larger option) to the V700's dimensions:

Tire---Size---Rim Width"---Section Width"---Overall Diameter"

Current
PS2---225/40-18---7.5-9---9.2---25.1
PS2---295/30-18---10-11---11.9---25

Larger
PS2---235/40-18---8-9.5---9.5---25.4
PS2---315/30-18---10.5-11.5---12.6---25.5

V700---225/40-18---7.5-9---9.1---24.9
V700---305/30-18---10.5-12---12.4---25

These front/rear combo's maintain similar tire overall diameters compatible with the AWD system, and i hear the Kumho's are sticky, good for summer driving. Thoughts?

Rassel

Best tires I've used for street so far is Michelin Pilot Sport Cup. (They stink in rain though...)

911/Q45

I have 235/40 and 315/30-18 Yoko A048s on 996tt rims with PSS-9s and they fit fine with no spacers, street type camber and plenty of clearance everywhere.

LT1

I couldn't get the 235 PS2's under my very low car. I found that PS2's seemed huge compared to my previous pirellis. I swapped them for 225 fronts.

V

Guys keep in mind that sometimes you are comparing apples to oranges here. LT1 is spot on that the Michelin PS2 is a bigger tyre compared to many of it's brothers and sisters but just because they rub on his car doesn't mean that 235 is too wide a tire for the front on a 993 TT. It has more to do with the section width (e.g rim width) and moreover the offset of the wheel itself.. Just my 2cents.. 235/40/18 front and 315/30/18 rear works fine on a 993TT with the 996TT wheels. No rubbing issues, even with the PS2's. Good luck

DM993tt

265 / 315 MPSC neg 2.5 all around.

LAT

My 993TT set up in Germany by RS Tuning runs 285/35 18" and 235/40 18" which are 25.9 and 25.4 respectively and RS considers these the ideal for the 993TT.

I am using Techart Formula wheels, 8.5" fronts and 10.5" rears with near stock offsets.

eclou

FWIW the Bridgestone RE050A's are even wider than the PS2's in the same sizes. -2.5 camber all 4 corners? Do the rears last longer than 1k miles?

NoSubEDU

I run a 245/40/18 tire on the front of the 993C2S but I have to remove the fender linings and use a 5mm spacer to clear the rub. I use a 295/30/18 rear. Considering going to a 305. All track use, car is low and has about -2.0F, -1.5R with 996TT rims. No spacers in the rear.

shawsan

I read so many posts on this subject because I wanted to complement the power upgrades on my 993TT (about 490HP now) with more rubber, particularly on the rear. I had Bridgestone S02s in OEM sizes 225s on front and 285s on the rear. Under WOT, the rears would hunker down but wheels would loose traction and/or the car would lurch in 1st, 2nd, even 3rd. It felt unstable, worrisome.

The problem is/was my car is lowered about an inch and 3 tire installers I visited were pretty sure that 235s wouldn't fit on the front, nor would 295 Michelin PS2s on the rear. I like the PS2s as I have them on my Ferrari Challenge Stradale, great tire. Nor would putting a 996 turbo wheel on my 993tt solve the problem, the 'lowering' issue just hampers things. Looks great btw, but lots of scraping also.

Anyway, put new Bridgestone RE050A pole position tires on yesterday and, yes, they do have a wider profile. Took the car out to my favorite "unstable" zone and hammered it, WOT coming out of an entry street in 1st, then 2nd. The car held. Praise "big buddy in the sky" and so I feel I made the right choice. Ok, new tire, newer design, but they held under WOT. Bilstein PSS10 Coilover System Porsche 993 Carrera & Turbo 93-98
[F4-GM5-D268-H0]

EThec

I'm also running 225 f and 295 r right now as i got a good deal on some 996tts take off wheels and tires a year ago or so. I was running 235/295's before and was really happy (no rubbing, no issues, car lowered on gert bilstein hd's and euro m030's) and was shopping for some replacement MPS PS2's for the rear when i came across the 996tts wheels and tires for $1k. That was like $200 over new rear tires alone and i love the 996tts wheels...... as much or more than the K18's i had. Anyway it was a no-brainer. i can't and never could walk away from my car without looking back. (how many car owners actually do this 4+ years into ownership?)....i digress. 600hp is a league beyond me, but when these Michelin Pilot Sport Ribs on the rear are cooked i'm taking the 235 MPS PS2's off my oem fronts and buying some 295's for the rears and sticking with the 996tts wheels....235's and 295's i think are a great combo for all around use. Anyway, just make sure the overall diameters work... (save the VC). If you plan to drive year round, watch out for a tire too wide. Hydroplaning is a real problem over 60mph in moderate rain. 315 seems too great for a 235 (i thought the rears should be slightly smaller in OD than the front).... but again you're dealing in a different realm than me and if 911/Q45 isn't having issues.... pm him. haven't been on here much lately, but i recall he's on the track often (laguna seca no less..... grew up going to the historic races there). Once got a few laps in a late '70's Ferrari GTB when i was not even a teenager. Man that was great.

Acropora

I have a set of 235/295 ps2's in storage just sitting. Since the car was tuned when I get on the gas in third gear or lower the car just does a 180 w/ the ps2's. Use 275/335 ra1's mostly now for the track and street.