This old-fashioned tool serves a number of purposes - A) It's a must-have for changing wheels. B) It's also useful for mocking a wheel on the hub to measure for spacer thickness. It's inserted into one of the bolt holes by hand and easily slides out when done.

A) This wheel pin (wheel stud) makes changing wheels a snap. When it's pressed into the wheel hub, the new wheel slides right over it and each bolt hole lines up perfectly. No more wrangling with a wheel/tire to get the bolts to line up! When done, slide it out of the wheel and replace it with a wheel bolt.

B) If you're trying to figure out what size spacer to use this tool can make things easier. With the pin pressed in to the hub you can then slide M12 washers over it to mimic the thickness of a spacer. The extra length of this pin allows you to slide the wheel back/forth to set the positon of the wheel. Measure the thickness of your washers and that's your spacer size! For this procedure, it's recommended that you have 2 of these pins so the wheel does not rotate out of position.