That's odd. I prefer it for 2 reasons: turns rubber very sticky when dry preventing tire rotation at lower psi. Dissipates moisture preventing rusty innards. I don't like soapy water inside my wheels.
Personally I use Nomar Bead lube, it's expensive but I change alot of tires in the summer so it gets paid for, and it works better than soapy water.
It would take a long time for WD-40 to actually eat through a tire carcus to the point where you could actually see the damage. The average rider out there changes his tires every season or two, I'm sure that for the amount of WD-40 actually used it wouldn't affect the structure of the tires during their lifespan, but personally I'm avoiding things like that when I can.
Spray some rubber trim or a clean tire with WD-40. Let it sit for a few minutes then take a clean cloth and wipe it off. The black on the cloth isn't dirt, it's the top layer of the rubber.
Aluminum rims aren't going to rust from a bit of soapy water.
After a few thousand km's of riding the heat cycles of the air inside the tires will vaporize any water in the tires. That's probably why when you take out the air valve to change the tire the air that comes out is moist and a bit funky smelling.
Topping up the air in a tire will always add moisture to the inside of the rim, depending on the temperature and humidity. The only way around that is to fill 'em with nitrogen, and I'm not ****'in spending 10 bucks per tire to inflate them.
Motorcycle steel rims are usually chrome plated, it takes at 10-15+ years to start getting surface rust on the inside, I've changed enough tires, I've only changed rims from the 70's and early 80's that were getting good surface rust.
Spoke rims are not air tight, hence the tube. Thus they are not water tight, moisture will get inside the rim no matter what.
I ran R10's for a couple track days last season, I know two guys who ran track with them as well. The rear tire moved plenty on the rim, for one friend almost 6 inches. This didn't affect the performance of the tire, there was no vibration for them. A couple track friend's mentioned that when you get your tires changed at the track they don't usually bother to balance the rear tire, there's no point with the vibration of the chain and sprocket moving around in the cush drive. I would assume that balancing the rear is more for optimal tire wear, which is more important for street riding.
Go to any motorcycle shop, ask them what lube they use to change tires, chances are they will say Sunlight dish soap. Go to any car shop and ask them what lube they use to change tires, they will say Sunlight dish soap
