XRAY - Model racing cars

Hi,

I use VTEC CPX tires on my T4 on a small and technical permanent carpet track with pretty high grip. The CPX tires here work usually well for a long time (At least 25-30 runs, I run 17.5T). Yesterday i wanted to run in a new set of tires. In the beginning I had absolutely no grip and even after 2 runs it was still very hard to drive the tires and I was about 20% slower than with me old used tires.
Is it normal that the CPX takes so long to run in? What are you experiences with it?
I use LRP Top Grip Carpet II additive and I do not heat the tires. Would you recommend heating the tires? And if so, which temperature do you recommend? Is there any other preparation of new CPX tires to make them work quicker? Otherwise I would need a totally different setup for new tires.

Thanks

It will be useful to cut the excess rubber material in the middle of the tire if you want to reduce run in time. It's hard to explain it for me since English isn't my native language, but imagine connecting two halves of a tire, where they meet the is a "line" of excess material on every new tyre.

The excessive material is there because there the two parts of the "mould" touch. Like on injection moulded composite parts.

Another reason for the missing performance of the tyres is probably that your older tyres were treaten again and again and again with additives. This long-time treatment increases performance as well. Do you clean your tyres with brake cleaner or tyre cleaner before applying the additive? Because if not the tyres just won't work.

I have the same effect at my home track for example. The CPX requires 5-10+ runs to get the best performance. As the foam insert becomes smaller (compressed) as the tires wear, increasing air gap, this also affects the performance. This can be seen most clearly at low traction tracks. At big events, the difference is not that big.

Thanks for your replies.
I m glad I m not the only one having that problem
Alex, how do you run your CPX tires in on big events if the tires are handed out? Usually there is not enough practice time to run in the tires for so many runs. Do the tires work so mich quicker for you on big events?

Normally 1-2 runs are necessary at those events. Some people sand off the sides of the tires to make them rounder, but according to some rules, this is considered as cheating.

Hi Alex,

thanks for the information.
Do you have any advice regarding the setup when changing from used to new CPX Tires as I will have a race with hand-out CPX tires soon. Are there any setup changes that can help to overcome the problems in the first runs?

Thanks