Have you had a tire weeping, crying or seeping at the sidewall? Don’t worry this is normal. We wish all tires were non-porous, but that is unfortunately just not the case. In fact, bike tire’s porosity is the exact reason that sealant was developed and needs to be used in tubeless ready setups. Puncture resistance is actually a bonus side effect! All sealants for tubeless set-ups contain a certain amount of a Glycol or similar additive for longevity. This can typically be seen coming through the sidewall in seemingly random wet splotches or dots of white or in even rarer cases in the form of “pin hole” bubbles. As the sealant does its job to seal the tire, air-retention increases over time. Below is a quote from one of our engineers here in Ohio.
“There is effectively 2 reasons as to why this happens, it was just installed and is too new, or it has aged and the sealant is too old. For remedying the fresh setup situation, customers should ride it a few days and see if it seals up. When dealing with this micro porosity in the sidewalls, the smaller the holes, the harder it is for the sealant to seal them up. Some sealants work better than others of course.
Regarding tires that do this after an extended period of time, that is caused by the sealant breaking down. If the sealant begins to separate (come out of solution), then it’s easier for the separate parts to start coming through the tire. We’ve seen that this can even occur through the tread on some tires they were riding even. Factors like heat, humidity, and riding frequency can all effect the rate at which this can happen.”
-Joe Angeli, Kenda Engineer