I had a chance to compare the OEM tires to Trofeo Rs at the ORP this past Saturday (4/29/17) and wanted to share my experience between the two:
COLD PSIs: 28 PSI for both setup
First of all, I have to mention that these are the best OEM tires I've ever had and I highly doubt if they're much different than the RE71R tires I had on my S2000 in terms of the grip level, time required to reach the target PSIs (or ideal temps) and consistency. They obviously did a great job for creating a dual purpose tire for both track and road. It also let me drive back home safely from the mountain passes and heavy rainstorm on the way back.
Another thing to mention is that weight and overall diameter of the two setups are not identical so there's still a margin of error if we don't take that into a consideration. OEM tire/wheel combo weighs about 7 and 8 lbs more than the Trofeo R track setup. Also Trofeo R wheel/tire combo is about 3% shorter than the OEM which makes the gear ratios a bit shorter (about 3.85-3.90 vs 3.73 stock) which is also beneficial at the track.
To compensate some of the advantages of the track setup, I decided to run the OEM setup in the morning sessions with a bit cooler ambient temps (high 40s vs mid to high 50s afternoon)
I did my personal best lap in the morning with the OEM setup and improved my previous best lap by almost 3 seconds at 1:55.8 (Rotrex Build BRZ with Z214s all around). After I put the Trofeo Rs I was able to shave additional 1.1 seconds and did 1:54.7. I could only do one session with the Trofeo Rs though so I should be able to do a bit better than that.
After a careful analysis, I noticed that I can try a bit different lines and gears for certain corners and so that I could improve it.
Other important thing to mention, in order to compensate the Front and Rear balance with the Trofeo Rs (305s square setup vs 285/305) due to amount of front grip, I decided to add the stealth wicker bill as I cannot currently use 325s with the current suspension and wheel. I think it did help me gain back some grip in the rear especially in longer turns. Being able to hit the target PSIs should also help however.
Overall, OEM tires performed great but it's possibly because it wasn't that warm in the morning and OEM tires work best when they're not overheated. After a consistent hot laps, however, I saw my hot PSIs reach to 39-40 psi up front then decided to get into cool down laps to preserve them.
Trofeo R, on the other hand feels like they may be a better match for warmer days (which is good for summer) and takes about full 2-3 laps to warm up with a bit different driving characteristics (slip angle). OEM after a few hot laps feel a bit lose but Trofeo R is bit sharper and allow you to brake late. Braking is also improved with the Trofeo Rs.
Another important different is the fact that as I was pushing the OEM tires I felt like they were getting a bit greasy and I felt like there's not much room left in those. Whereas with the Trofeo Rs, I could only do one session and tires and overheating was not an issue. The overall gap might be slightly bigger than 1.1 seconds in a 2 minute lap course because of that.
Here's a video from the event, comparing the best laps of the two setups:
Update: (2017/6/14)
I finally had a chance to compare the all three tires. I did my third event with the NT01s (305/325s) .
Which one is the best tires/setup of all three? Well, the answer is "it depends". They are all very close but with very different driving characteristics/slip angles. It's somewhat easier to rotate with the NT01s and being able to go full throttle at the corner exit sooner than the others. Thanks to the additional grip in the rear with 325s. This however becomes a bit disadvantage at the ORP since gears are a bit longer than the Trofeo Rs which makes me alter the shifting points and possibly cause some time because of that.
In terms of lap times, I believe the lighter and a bit more heat resistant Trofeo Rs will have the advantage on the tighter courses with a lot of body weight transfer such as ORP. No wonder I did my best lap at the ORP with this setup.
However, on a faster course where I can use additional grip in rear such as Ridge (RMP) NT01s felt faster. I didn't use the OEM setup at the ridge but I wouldn't be surprised if it would match my best time with the Trofeo Rs there since the overall feel was better.
In short, for the best overall tire and streetability I would still pick the OEM wheels and tire combo. Especially if you want to keep just one set of tires and wheels. Our MRC suspension calibration is based on that OEM tire/wheel setup anyways.
If you can get a dedicated track tire/wheel setup however, going with wider NT01s might be better in terms of overall lap times and to fight with understeer up front. It's just so much fun driving NT01s but when the track conditions are hot be ready to put your best lap after the warm up lap or 2nd or 3rd lap. I am not saying they overheat like most street tires like OEM or RE71Rs but the optimal lap times (in all the cars that I've tried NT01s previously) was when they're relatively cooler.
Trofeo R driving characteristics didn't really impress me a lot. I could definitely feel the softer sidewall or softer feel of the tires compared to OEM and NT01s. However, weight and gearing advantage (3% shorter gears vs 1.5% shorter gears on NT01 with 5 lbs additional weight on each corner) is very noticeable. Although, I couldn't get on the throttle as early as the NT01s once I did it was quicker on the straightaways and easily make up for that. It just didn't feel right or enjoyable to me. They're also expensive
I have to note though, I didn't have the -2.9 camber up front with the OEM setup or the Trofeo Rs so there may be a slight advantage there.
I did 1:54.9 at the last event at the ORP with the 305/325s NT01s. It was a warmer day than the last time I used Trofeo Rs there and did 1:54.7. Notice how easy to rotate the car with throttle and the different slip angles:
I hope this helps
