If you are a good driver, the tire change on that course will only save you about 1.5 - 2 seconds a lap. Once your tires get in the red they do not get any worse. So it does not matter if you pit at 35 the last 25 laps your tires were as bad as they can get. I tested this on the enduro. To help cure my boredom. I changed my tires and tried several laps my best and then let them get bad and I could average 1.4 - 1.8 longer laps with 100% bad tires. Now I would look to see how much the two laps were slowed down. And the pit stop does not come close to making up for your gain in corner speed. This was in a previous post of mine, this is one of the things they could improve on the next one, to make it so you blow your tires if you ride in the red for to long. Anyhow I think I answered your question. Do not even bother pittingn if it is every 35 laps. Because your tires last 10 laps tops. I went 70 laps on my last set and still won by many laps.