Venue: Silverstone Grand Prix Circuit
Date: 6th May 2013
Tyres tested: Toyo R888 285/35 R20 front and 315/30 R20 rear GG medium hard compound
Inflation: 100% vacuum nitrogen to 30lbs all round
Ambient temperature: 21c
Track temperature: 29c
Humidity: 34% (low)
Drivers: Jake Hill for the analysed test and John Miskin for an amateur’s perspective
As this test was carried out at Silverstone during an official track day, lap timing is forbidden and the car was equipped with a V-Box that collected the data which was downloaded later. This data did include lap times but this was coincidental and was interrogated after the event! This test is also undertaken with the view that the results were those that GTROC members would understand and relate to rather than a cold scientific and analytical one that could have been done under more controlled conditions.
The car was initially run on a set of Michelin Pilot Super Sports (MPSS) with all tyres inflated to 30lb cold and again filled with nitrogen from a vacuum environment. As I have already stated in previous posts, I believe these tyres to be the very best for the GT-R for all road use and some track events. Only when pushed really hard will the weakness of the sidewalls become apparent and a small amount of bounce under heavy braking and on fast uneven corners. The car has to be driven at 10/10ths on the track to find the tyres weakness and that is exactly what I did, and the pressures rose dramatically after five fast laps. This causes the tyre to expand and puts particular pressure on the front tyres and the centre tread can start to roll and disintegrate. Therefore the conclusion is that for owners that will only do the occasional track event or just use the car for fast exhilarating drives, then the MPSS will not disappoint especially in the wet.
The Toyo tyres were fitted when the track cleared during lunch break and Jake Hill took the car out with me as a passenger. One slow warm up lap followed by another that gradually built up speed culminating in one fast corner close to the limit and then one standard in lap. Tyre pressures were checked and the fronts had gone up to between 36psi and 38psi and the rears 34psi and 35psi. The temperatures were at 78c front and 64c rear. The pressures were lowered to 33lb all-round and the car then went out for five fast laps and the results were extremely good. Technically, the pressures rose by a further 3lbs at the front and 2lbs at the rear, and the tyre temperatures increased to just above 100c on the front (101c nearside and 107c offside)and just under 90c on the rears (87c nearside and 90c offside). As a passenger I felt the car gripping a lot more and Jake was able to carry more speed through the fast corners. Jake’s comments were as follows:
“The car felt absolutely mega on the Toyo’s once they had got hot and been through a good heat cycle and scrubbing in process. The tyres felt like they were runflats as the strength in the sidewalls was immense and there was no bounce under braking or on the fast corners. The grip came in very quickly and maintained their best for four fast laps. After this, I could feel a little fall off, particularly from the front as the car started to feel a little more understeery but still vastly better than the Michelin’s. Probably the best aspect was the complete feel that I got from the tyres and the controllability in the fast corners. I felt confident that I could induce both oversteer and understeer in a fun and controllable way. I think I pushed too hard at the end and had to brake from over 150mph to 40mph in a very short distance to avoid a slow car that came across me. The car behaved so well with this mega braking without any bounce and I couldn’t get the ABS to come in and I am sure this is partly due to the new brakes, but a complete contrast to the Michelins. The closest to these Toyo’s are the standard Dunlop’s, but then everything would have been done at slower speeds and with less confidence. Having done many laps in John’s car on Dunlop’s, I can confidently say that the Toyo’s are almost like slicks and behaved like slicks, with the importance of scrubbing them in and completing a correct heat cycle, while the Dunlop’s are the second best on track and may stay at their optimum a little longer. However, after 15 minutes and allowing the car and Toyo tyres to cool down, I went out again and the tyres were back to their best on the second lap. My only other comment which may be useful is that having driven over 20 different GT-R’s on track with different tyres, I believe that the most unpredictable are the Bridgestone’s, the most consistent are the Dunlop’s and the best track tyre by a measured mile are the Toyo 888’s. I have seen John go through a set of Dunlop’s in a day and the Toyo’s did 28 laps and still looked good even though they only start with 5mm of tread compared with 7mm on normal road tyres. I do not know how the Toyo’s would last on a full track day doing 70 laps + but believe that they would maintain their overall performance. It is a pity that these tyres couldn’t be tested in the wet, but having spoken with some fellow racing drivers, the opinion is that once some heat has been generated, the Toyo’s outpaced many other cars on intermediates”
That was Jake’s opinion and the V-Box showed some very positive results with four of the fast corners on the Grand Prix circuit showing increased speeds and higher lateral G forces. These figures were taken from the optimised combination of the laps.
Copse Corner – increase of 11mph and 0.4 lateral G more
Stowe Corner – increase of 9mph and 0.3 lateral G more
Abbey – increase of 4mph and 0.1 lateral G more
Farm – increase of 12mph and 0.5 lateral G more
The slow corners were virtually identical taking all the laps into account, but the braking was started a little later. This could have been partly due to the new brakes but probably more to do with confidence and the stability under braking.
Unfortunately, there wasn’t one clear lap during this tyre test, so the figures have been taken from the optimum lap as were the figures that were used as a baseline from the Michelin’s.
Surprisingly, I pulled up some figures that I had achieved last year at the end of July when the weather conditions were similar, and I was running a new set of Dunlop’s at the time. The car was not running quite as much power but the times were virtually identical to those when on the Michelin’s, which shows that the Michelin’s have the grip but cannot take the punishment. As far as noise is concerned, Anders and I took the GT-R to Brackley for fuel and the noise wasn’t too bad and improved as the race rubber and pick up/rolled rubber had cleared. There was a distinct whine from the Toyo’s but this was acceptable.
Michelin are best for normal road use with less tramlining and better wet weather characteristics. The Toyo 888’s are the best for pure track use in the dry, and they should be OK in the wet but this hasn’t been tested. I have to admit that I did my fastest lap ever on the Silverstone Grand Prix circuit by nearly five seconds after Jake handed the car back to me on the Toyo’s. The OEM Dunlop’s are good for both road and track and generally it has to be understood that the tyres were developed for the car and Nissan still state that runflats should be used and the Dunlop’s are the only tyre recommended for the vehicle. The Litchfield suspension kit certainly improves the ride and turn in for the Dunlop’s and it complements the Michelin’s as well. In my opinion it is a brave man who runs the RE70 Bridgestone’s, especially when they are part worn and in cold wet conditions. I also understand that many members think the Bridgestone’s are great and they are priced competitively, so it is subjective.