The wrinkled bits are a combination of the latex stretching to fit into the little negative space under the bead, made permanent by exposure to brake heat. In most setups you will have 2 rows of this wrinkled area, and as your rim tape moves side to side you may see the wrinkles move similarly.
The ideal latex setup has a high quality rim tape running the full width of the rim to that it runs under the tire bead, and if the sides of the tire well are deep enough, you ideally want the tape to go up the side a bit to give you added protection in that interior corner under the bead.
It's amazing how effective even a thin rim tape is at knocking down the surface temperatures inside of the system. Remember, Latex has a max temperature rating of around 240-260F depending on formulation and lightweight rims can easily heat soak into the mid 300's at the brake track during serious descending and can briefly hit the high 200's with a single panic stop from high speed on flat ground.
Tubeless tape has a few key advantages here:
1. It is thinner than traditional tapes so that it makes tire installation easier = you're less likely to pinch the tube
2. It's smooth which is important in allowing the latest tube to be moved into position without any stickiness that can cause a pinch during install
3. It comes in widths so that you can buy it wide enough for your rim, and it's flexible enough that it can be run slightly wider than normal for added protection, i.e. I have 303's which came with 19mm plastic rim tape which I've replaced with 21mm tubeless tape that runs the full width of the tire well and comes up the side of the bead about 1mm. With Vittoria Corsa G+ there is no latex-carbon contact with this setup and pulling the tubes out after months of use shows ever so slight deformation in the tube from expanding into the little corner at the bottom of the bead, but none of the heat-damage wrinkling.
4. It is wrapped on in layers, so you get a slight added insulating effect of having numerous layers and interfaces which makes for less efficient heat transfer than you get from a single ply of plastic, and also you can tune it to your conditions. I run 2 layers of SILCA Platinum in all my wheels, but know some heavier guys who live in places hillier than Indiana and they will run 3-4 plies depending on the tire/rim combination.
The best way to think of it is that the rim tape is a form of insulation that's essentially buying you time under heavy braking. In the Ultimate Failure testing model we built at Zipp and have shared with the industry, the wheel is driven at over 1000 watts against the brake pads and the goal is to last a certain amount of time to prove the system is safe. It is common to see butyl tubes with plastic rim tape fail at 3-4 minutes and latex tubes fail at around 2-3 minutes with standard rim tapes...getting the proper width of tubeless tape at 2 plies can extend the life of the latex to more like 3-3:30 and then each additional ply of rim tape can add another 20-30 seconds. So latex with 3 plies of properly sized tubeless tape can last as long as a butyl tube with stock rim tape.
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