RE: scared tank slapping

[davipu]

ok so take some glass cleaner and spray it on the sides of the tire, find the leak it can only be a couple of things, most likely it is a bead that isn't seated. or maybe a valve stem core that went bad.  and hey, if your not comfortable riding on crappy tires stay off the bike. when you get new ones though I want your old ones I'll pay shipping.

[Eklipse]

Mine doesn't usually do it when I let go of the bars, only occasionally. I've had it happen at all varieties of speed. And from wobble to almost a full on tank slap. Haven't had anything bad happen but definitely makes you want to grab the handlebars again.

[Copcorn]

If the tires are hard, old, cracked etc, replace them.  

I had a BMW that wobbled just as you described at about 30 mph.  I thought that something might be wrong, and I asked other owners of the same bike.  Turns out that everybody had the same wobble.  It wasn't scary or uncontrolable, but it was there.  That was just the speed that that model wobbled at.

Because of a low tire and overloading, the bike once wobbled at 65 mph.  That was scary, but I controled the bike and fixed the problem.

I have heard many stories about older Harley Sportsters.  They seem to wobble at 90-100 mph.  At that speed, there is enough energy to rip the bars out of your hands and throw you off the bike.  A guy I ride with witnessed this when a friend of his tried to "accelerate past the wobble".  He got thrown, and a ton of road rash.  Then the guy picked up the damaged but rideable bike and decided to get back on the horse and try again, with the same result, and a lot more road rash.  He died a few days later.

If everything is in good condition, I wouldn't worry about a 30 mph wobble.  It probabaly means that you don't have a wobble at 100 mph!

[scratch]

Yep, better to be safe than sorry. Good, wise choice. Also, one more thing, grip the tank with your knees.