How do you tell if a used wheel is straight?
 

I am looking at used wheels to use with snows. If you're at a swap meet or somewhere else where the wheel isn't on the car, what's an easy way to tell if It's straight and true? I don't want to end up with something that wobbles or won't balance.

Put it on a flat surface? (face down, and look for gaps)

Roll it and watch...

JR

Unless you have a spindle to rotate it on, the only thing you might try is a continuation of Geronimo's advice. Do that and also see if you can detect any variation in the mounting surface in the wheel center and the flat surface you have the wheel resting on.
You have two ways for it to deviate from running 'true': either deformation of the rim itself or mis-alignment (usually through bending) between the center and the rim.

I wouldn't be comfortable unless I was able to spin it.
Les

This is what I am most concerned about, and what would be the most likely situation.

People buy used wheels all the time, do they just take their chances?

Look at the wheel weights. If there is a lot on one side it's bent. If there is weight on one side of the wheel, and weight perpendicular or to its 11, or 1 O'clock. Then it's also bent.

Put it up next to a wheel of the opposite gender?

HA!

I am looking for Miata wheels. :D

Well, those are never straight. Just try to find four of them that get along.

JR