Originally Posted by
mlh122
one of the benefits of V-Brakes, helps keep the rims true
I've seen tires that wobble to the left and to the right a little, but I'd agree with everyone else, if you're doing jumps with stock wheels they are probably out of true.
It might be tough to eyeball trueness if you have disc brakes. You could try gripping the fork firmly with your hand and pointing your index finger at the rim until its like 1mm or so from the rim. then (while firmly holding your hand in that position) spin the wheel, if it intermittently touches your finger, your rim is out of true.
I have an old school aluminum mongoose 26 in 21 speed that I rebuilt several times some used and New parts. I've tought myself to true and then to build wheels. I don't have a truing stand so I made a tool out of an old spoke that wraps around the fork. Take the tire and tube off and replace the wheel.put the tool on the fork so it's as close as I can be without rubbing the wheel. Spin the wheel and with marks put on the tool will show where the center is and where the edges of the rims are. Also since it's just wrapped around the fork it's easily moved to show high spots. Not perfect but works for me