Jesper64 wrote:If you're on clincher tyres then latex tubes can save quite a few grams over butyl.
The main difference is that buty rubber is used to make every category of tube from light racing to super-heavy thorn proof. Latex, OTOH, is used essentially only for racing tires. So you have to be careful when buying butyl tubes to seek out the lightest if that is what you want. When buying latex tubes, they are all reasonably light. I think that is what is responsible for the impression that latex tubes are generally much lighter than butyl. It just isn't true at the ultimate low end of both.
There are readily available 70 g butyl tubes from Performance or others even with 48 mm valve stems. Vredestein has a 44 g latex tube, but many others are heavier than the 70 g Performance butyl tube like Vittoria's. There used to be a 52 g butyl tube at Performance with the 48 mm stem, but it was unreliable at the seams and was discontinued. Thing is butyl rubber and natural rubber (latex) aren't really much different in density. The formulations both contain oil and fillers as well and the curing agents. I doubt one should make much lighter tubes than the other.