i've searched and even posted this on other threads, but can't get a straight answer...most guys' cars are lowered or have similar but not the exact same tire sizes so they don't quite apply to mine.

i have an otherwise stock 996TT with 997.1TT wheels with 7mm spacers up front and 15mm spacers in back. i had great luck with the requisite 235/35 and 315/25 PS2's to minimize front diff damage, but now i need new tires, and the 315/25 are so hard to find and/or expensive that i want to change sizing altogether and go with pilot super sports.

my options, as i see it, are 225/40/19 and 305/30/19 (or 295/30/19). this is essentially the same as OEM but on 19's instead of 18's, the circumferences and revs/mile match, and i'm pretty sure these will fit in the rear, but i'm concerned about the front. alternatively, i could do 245/35/19, but then i'd be restricted to 295/30/19 in the rear. therefore i like the idea of 225/40 so i could go between 305/30 and 295/30 depending on availability/price/etc.

question is: will the 225/40/19's rub anywhere? i'm afraid they may be a bit tall. or will the 245/35/19's rub? i'm afraid they may be a bit too wide.

btw, the car is a daily driver and i do 3-4 track events/year.

thx in advance

 

I have Champion RG5s with 235/35-19 and 305/30-19. I had to run a 5mm spacer on the rears so I don't rub, they do fit perfectly fine otherwise. I'm about to lower with H&R and it should actually give me more clearance in the back inside (as it rubs the lower part of the liner not upper) appears moving the wheel up in the well will help. Once lowered the fenders get close to the tires and rub there, I'll probably have to roll the fenders a bit which is easy to do.

As for tires sizes, some guys go on about revs per mile etc but keep in mind there is no proof it does anything. There are lots of guys on this forum and I have seen hundreds of cars at shows with non matched tires who don't have issues. At this point, the rev per mile is all hersay as there is a lot more proof there is no problem than otherwise. We have what 2-3 guys who blew diffs? They are viscous diffs, they blow for no reason (because they are ****) so the very few examples we do have could have blown for any number of reason.

With that said, when I buy tires I will try and match as best I can just cause I understand the mechanics behind it. Lets say I'm not losing sleep about my current setup however. Think I'm gonna try a 235/40-19 which would match the 305 rear almost perfectly.

Disclaimer: Just my opinion, no need to start a flame war over facts vs. opinions and he said / she said etc. And please, nobody post the link to the "Front diff chewed due to incorrect wheel/tire setup" thread please. It's so full of hearsay...

 

i appreciate your insight and that's a very good point about the lack of "proof"...but if i had mismatched tires and my front diff went out (regardless of the cause), i'd be kicking myself b/c i took on that [albeit small] risk. if my diff goes out for no reason with matched tires, then i can sleep soundly knowing it was going to happen anyway and i did everything i could to prevent it.

glad to hear the 305/30's work as i've heard they do and suspected they would stock suspension and spacers. i'm still mostly concerned with the 225/40 (height) vs 245/35 (width) up front. know of anyone with experience with either of these? they're going on the car tomorrow and i have a track event in indy this weekend!!

 

Attached is a pic of my 235/35 and 305/30 setup on stock suspension. There is TONNES of room on the front, I felt around the wheel and I could run a lot wider or taller no problem. Don't see how you'll have trouble with the tire you're looking to run.

 

I just returned a pair of yokohama advan sport 315/25-19 to tirerack if you're interested. i'm going with the "steve k ny spec" 305/30-19 rear and 245/35-19 in the front michelin pilot supersports my car is in the shop right now for H&R street coilover installation and possibly a rwd conversion (shop owner is not too crazy about cutting the axles). still... 305/30-19 and 245/35-19 is the closest you'll get to the recommended 315/25 -235/35.

 

here's member dhalen's car with 305/30-19 and 245/35-19


here's a nice comparison picture 315/25 vs. 305/30 from member ssmugen

 

that's funny b/c i currently have 235/35/19 plus 7mm spacers and when i felt up in there i agree there is tons of room between the tire and fender, but barely the tip of my finger would fit between the tire and the lower spring perch on the shock...and that's what i'm worried about.

i had already seen dhalen's car (which is pretty freakin sweet, btw) on another related thread, but his set up isn't exactly what i'm looking for. while i'm glad to hear both the 245/35/19 and 305/30/19 work, i'd prefer not to run those together b/c they're 783.2 and 769.6 revs/mi, respectively which is 13.6 or 1.7% difference. i'd like to stay closer than that (under 1%) b/c the diff failure reportedly happens with 235/35 and 305/30 which is 22 revs/mi or 2.8%. 1.7% is a bit too close to 2.8% for my comfort level.

hopefully it all works out. we shall see tomorrow morning. we're going to start with the 225/40/19. if that doesn't work, we'll try the 245/35/19.

thx for the supportive words, tho guys. i'll sleep better tonight knowing it should work...that is, if i even get the chance to sleep which is unlikley considering i'm on 24 hour call at a trauma hospital...FML

 

Just an FYI... i'm 2WD... front axles are gone... Not too sure if i'd run the same 235/35/19 setup if I had AWD.

 

i had the pilot super sports 225/40/19 and 295/30/19 installed on wednesday of last week, drove from ATL to Indianapolis on friday, ran a track event at Putnam Park (outside of Indy) all day saturday and sunday, and drove back to ATL on monday.

and NOTHING RUBBED!!!! not the fender liner, not the fender itself, not the suspension, nothing. and the tires performed great and seemed to hold up well.

so this is another readily available, reasonably priced option as opposed to the ridiculously expensive and hard to find 315/25/19 and 235/35/19 combo.

the only thing to keep in mind is that they're 1" taller/circumference than OEM so the speedo is ~4-5% slower than your actual speed...but so is the mileage

 

Sounds great doc! If you can comment on the pilot super sports, that would be awesome too since I have them as well in 305/30r19 and 245/35r19 soon to be installed. $70 rebate from michelin this month if you buy all 4 tires.

 

they did great: cornering, braking, everything. however, it was my first time on that particular track so i wasn't out to set any land speed records (rather...my only goal was to arrive back home "shiny side up" as they say), but they certainly held up as hard as i pushed them. there wasn't as much tire squeal as with my PS2's, but that could be attributable to different pavement between tracks or my driving style between events or other conditions. i never skidded out or crazily broke loose or anything, but again, i was only driving at 80% b/c i wasn't entirely familiar with the subtleties of the track. when i get them down here at my home track (Road Atlanta) i'll be able to provide more insight.

tread life seemed good. of course i wore down the outside shoulder tread block a little from being under inflated early on saturday, but that's expected. i started off with 15/32nds depth in the deepest center groove on all 4 corners. after the event, the rears were still 15 and, interestingly, the fronts were closer to 14/32nds. i also put about 1200 highway miles on them (from ATL to Indy and back) and they did fine. no noticeable noise/drone, no pulling to one side or another, etc. they were perfect on the highway. it only sprinkled a bit so i can't really comment on real rain performance.

hope this helps. all in all, i'd say they were great. as good as PS2's if not better...and 1/2 the cost (compared to 315/25/19, anyway)!!!

side note: the local porsche dealer had a couple of 981 Cayman S's out there with professional drivers giving free ride-alongs. they were bone stock, had PDK, and were on pilot super sports. they took me for a ride in one and it was freaking amazing. it was unbelievable what they were doing in that car on those (street) tires. they were passing highly modified 997 GT3 RS's with R compound tires. obviously it's all about the driver, but the point is, the cars were still doing all that on pilot super sports. that alone makes me very comfortable with their performance, regardless of what they felt like on my car with my dumb *** behind the wheel!

 

Great write up doc! I always thought PS2's were the gold standard but you make the super sports sound like they're right up there. Plus, it's nice to know that 996tt's with 19's and proper tires can be competent on the track. A lof of people have been saying 19's for the street and 18's for the track. I still have the oem 18's but it's nice to know I can track the car with whatever size wheel. As you said, it all comes down to the driver, not the car.

 

i thought so too, but michelin themselves rank the super sports higher than the PS2's...i think they may be phasing out the PS2's.

http://www.michelinman.com/tire-sele...formance-sport

either way, i'd say they were quite competent street/track tires (assuming you don't want to get into R compound). the 18 vs 19's is a popular debate and most ppl agree that 18's are "better" b/c of more sidewall, more forgiving, less weight (in the wheels, anyway, but heavier tire), etc, and 19's clearly look better but provide rougher ride, etc. for me, the 19's are fine for my purposes.

i really didn't like the turbo twist OEM wheels and i LOVE the look of the 997 wheels so that's why i made the switch. the size just happened to be 19, but that wasn't a determining factor for me. in an ideal world i wouldn't have sold my 18's and they'd now be my track wheels with R compound tires...but when i sold them, I lived in a condo and didn't have space for and extra set of wheels/tires. so now i'm left with one set which is why i'm tracking it on super sports...and i'm too cheap to put money into another set of wheels and R compounds for now. to be honest, i don't even know how much more i'm going to track this car. it's in perfect condition and i'm getting nervous about beating it up. i'll keep it as a garage queen and probably get into an e46 ///M3 for the track b/c it'd cheaper to insure/maintain, and i wouldn't care about smacking it around.

 

Hey Doc, thanks for the insight, this is perfect! I just spent the last 2 days reading tons of opinions but nobody had actually run the setup you have. I have a set of 997tt wheels coming to me and have been trying to determine what size tires to run and I wasn't crazy about running 25 series in the rear.

Anyway, I just have one question, what size spacers are you running in the front and rear?

 

I have (already) 997.1 wheels and 235/35/19 and 305/30/19 mounted, not in the car... (that is2.779% diference) do they afect my AWD ???

just want to be sure before i mont them in my car...

thanks for your quick answer.....