Bridgestone YLR's for ROK series

Does anyone know what “category” (soft? medium? hard?) the ROK series Bridgestone YLR’s fall into? I have been using MG Yellows on my Zanardi KZ2/Rotax Evo for some time and have some data points as to handling and the life of the tires. I have a new CRG KT2/ROK VLR 100 and I first rolled out with MG Yellows; they have 81 laps on them now and still appear to have some life – no cording and good grain pattern. I took them off to try the spec Challenge of the Americas tires, the Bridgestone YLR’s. Again, good grain pattern. However, one of the rear tires is just showing a diagonal line of cording after just 46 laps. Both sets of tires have only been driven at our Tucson (reportedly high speed) track in HOT Arizona weather.

The YLR tires are in my opinion medium tires. The problem with them is that they tend to crack or “fall apart”, and different tire batches from the factory also sometimes have different grip levels.
The tires are nice, soft and stable for the first 40 laps, but then after about 50 laps they really start to get weird, and Sometimes crack

That “crack” is the delamination at the seam of the tread from how it is made. Most times this delamination doesn’t cause any issues, unless it continues to delaminate. Usually this happens if there was contamination during the manufacturing process I’ve been told. Last year I used the YLRs as my practice tires because I could put so many laps on them, probably put 150-200 laps on my shifter on them practicing.

I know tyres vary in batches, but i had a set of YLR tyres that were the best tyres i have ever had , i did personal bests over two different races and they lasted up to 80 laps without dropping off. I would say they are medium soft and were quicker than mg yellow or vega green. We were running at 35oC air temperature. I was sorry to let them go.

Personally I love hard tires. I think the rental compound gives the correct amount of grip for the power. I adore the fact that grip is constant throughout the life of the tire. Once you get em up to temp, they stay exactly the same, assuming you take care of them. And, they go forever. Brilliant!

I have often wondered what TAG would be like on less grippy tires.

First, thank you guys for replying. Second, I do not know what an engineer would do with this info – everything from (1) tires dropping off after 40 + or - laps to (2) “best tyres i ever had” with personal bests and 80 laps to (3) up to 200 laps on a shifter. What???

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