ExMB

Bad idea to mix different tires from different manufacturer's with obviously different rubber compounds.

rraustin

How much oversteer are you getting with the Trofeo R's? Generally speaking on the track you want the balance of the car to lean toward oversteer in order to be able to rotate the car as needed to get the right apex angle.

Eric5280

Just give in to the power of the 19's. Everyone's doing it.

DeerHunter

You should really clean your garage. And your car. Disgusting!

On topic: It's a shame the GT4 didn't come standard with 19" wheels. This OEM predilection for over-sized boat anchors is unfortunate.

usctrojanGT3

Here are pictures of my RE71R fronts before getting them changed out....22 HCs and 1,200 total miles.

usctrojanGT3

+981...not sure why some of you guys are slow rolling on getting 19s.

orthojoe

Read below. Looks like it's no different between GT3 and GT4.

That is EXACTLY the same pattern that I found running cup2 vs TrofeoR on the GT3. EXACTLY.

Honestly, that exact thought has crossed my mind using the exact same rationale you just posted. I just couldn't bring myself to do it because it violates some basic rules even though it makes sense on paper. I didn't want to be a guinea pig for that one...

mad oversteer after 1.5-2 track days. Lap times slow down by 5 seconds.

Damn it. That looks awesome. I remember running NT01s and having wear like that. Although, your higher spring rates could account for the nice even wear?

Leong72

Thanks. I ask because on three of the five straight on our local track I redline in third or fourth. If the gearing is slightly lower then it could necessitate six extra changes per lap.

It was turn in oversteer. Not as bad as what Joe had by any means. Just unsettling as our track has two downhill turns and the car rotating too much such that it was hard to be consistent in getting the angle right as you come off the brakes. Still working on this as a driver.

I'd had the bars F soft, R med with the MSPC2s. We hardened the front to medium and that cured the turn in oversteer, and the feeling like the tyres were rolling over on the shoulders, but then had understeer on exit. Hardening the rear bar solved this so I'm happy with the way it now handles. Seemed pretty good in the rain yesterday too.

Maybe... but I might wait like Joe. Don't have the room to store 4 OEM wheels, two half worn sets of rears...

Love the wear pattern and hopefully the tyres handled the same throughout the 22 HCs, Great for a track only car, but if this were a dual duty car, those tyres wouldn't be legal for the road.... am I missing something? Perhaps cost, I have no idea on the cost difference...


I wasn't sure if that rule applied front/rear... I mean we run different width and profile front to rear, some cars run different size wheels front rear, but always the same on the same axle. I'm not keen on being a guinea pig either, given possible consequences

jphughan

Well the fact that those tires are worn to the point that they wouldn't be road-legal is probably partly why they're about to be replaced, or at least wouldn't be driven in the wet until replacement. But as you say, I think it's promising to see wear so even across the tire, which I think was the point of the post. Cost delta isn't totally certain yet since the RE-71R isn't available in the GT4's OEM rear size yet, but looking at the front size on Tire Rack, Cup 2 N0 runs $472 apiece, and RE-71R runs $278. In fairness, the Cup 2 Ferrari spec of the same size runs $305, but I don't know what the differences are. I remember a detailed post from a Tire Rack employee here comparing the original Cups and finding that many of the N0 changes were around wet handling, which I'd like to have based on my usage of the car, but I don't know if that persists for Cup 2. Orthojoe has said he's faster on N0 than Ferrari spec though. The "Porsche tax" on the rear Cup 2s isn't quite as steep compared to the Mercedes spec available in that size ($552 rather than $485), but whatever the RE-71R will cost in GT4 rear size, I think it's safe to say that the savings will be significant if you would otherwise run N-spec Cup 2s in order to maintain a consistent tread/compound design front to rear. But even if you don't care about N-spec on Cup 2s and are ok running Ferrari spec on the front and Mercedes on the rear, the RE-71R will still likely be cheaper. The fact that usctrojangt3 has previously said that they're as fast or faster than Cup 2s in the dry AND usable in the rain AND seem to last a bit longer seals the deal for me. I'll definitely be trying a set when they're available.

Different tire widths and diameters will affect total grip levels and of course aesthetics, but not broader grip characteristics. For example, if one tire is significantly grippier than the other in the rain due to its groove pattern, you could end up with a very loose front or rear in that situation, and in fact the OPPOSITE end would probably be loose on the track in the dry because more grooves for improved wet traction typically means smaller contiguous contact blocks, although of course the compound of the rubber itself has to be taken into account. And then there are differences like how quickly grip falls away once you've exceeded the limit. I'm fine running different widths/diameters front to rear, but not completely different compounds and tire designs.

BillC3

My limited experience with the Dunlops is the fronts wear very quickly. It only took about two hours of track time to completely wear the center ribs out of both front tires. The rears, on the other hand, looked great -- very even wear and could easily last twice as long as the fronts. So, I'm done with the Dunlops. Replaced the tires on the stock rims with SuperSports for DD'ing, and have RE-71Rs and 19" rims on order for track use.

BTW, what pressures do y'all recommend for track use with the RE-71Rs (both hot and starting cold)? Thanks!

Eric5280

Dunlops after 21 HC's

Eric5280

orthojoe

My dunlops after 10 HC at MRLS on the GT3:

Eric5280

Nice! That's some good work, Joe. Mine looked similar to that after 10-12 but then I dropped the pressures to 29 hot and the wear evened out and moved to the edges. 33-34 was too much it seems. DSC Sport unit helped last time out with wear a little as well.

orthojoe

Yes, I had been told by someone that the dunlops were designed to run at higher pressures than the cup2. However, as I hear more and more, it appears that the information was not correct. One of these days I might give the dunlops another shot