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Is there a simple/inexpensive tool I could buy at like Kragen or NAPA that could tell if the wheel is pretty straight? I don't know what to search for when I go in to a parts store or what to ask for, and I know I heard that something like this exists.

Looked at some used rims yesterday, and need to check them for straightness, w/o using a piece of string and a ruler....
 

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Not that I'm aware of. The best method I've ever seen is to mount the wheel on a device you know is perpendicular to the floor, put a metal straight edge on a levelled platform and in contact with the face (and then the back) of the wheel, and measure the gaps. It ain't easy. Nonetheless, the less exact method I've always used is to mount the wheel on a wheel balancer and spin it at high speed. If there's significant run-out you'll see it. It's hard to measure anyway, because most run-out specs I've seen is <= .05 inches. Try measuring that! :)
 

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BMcCoupe said:
Is there a simple/inexpensive tool I could buy at like Kragen or NAPA that could tell if the wheel is pretty straight? I don't know what to search for when I go in to a parts store or what to ask for, and I know I heard that something like this exists.

Looked at some used rims yesterday, and need to check them for straightness, w/o using a piece of string and a ruler....
You could use a dial indicator with stand.

I've printed out the info you need. Will post it when I get a chance to scan the 12 or so pages.
For one-part alloy wheels the spec is:
Max. radial runout of rim is 0.3 mm = .012"
Max. axial runout of rim is the same .012"
 

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I've printed out the info you need. Will post it when I get a chance to scan the 12 or so pages.
For One-part alloy wheels the spec is:
Max. radial runout of rim is 0.3 mm = .012"
Max. axial runout of rim is the same .012"
12 pages, eh? Well, so much for a simple procedure! :D

I'm also surprised at that spec... .012"... I hadn't seen that. That is one tight spec for cast wheels. My guess is that very few aftermarket 1pc wheels could meet it. Given the typical run-out for radial tires it makes you wonder why such a tight wheel spec is necessary.
 

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IMR said:
12 pages, eh? Well, so much for a simple procedure! :D

I'm also surprised at that spec... .012"... I hadn't seen that. That is one tight spec for cast wheels. My guess is that very few aftermarket 1pc wheels could meet it. Given the typical run-out for radial tires it makes you wonder why such a tight wheel spec is necessary.
The procedure is basically a dial indicator on a stand.
The spec with tire is 1.1 radial and 1.3 mm axial.
 

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For the record, a similar question was asked over here today...
> E39 (1997 - 2003) > What home wheel measuring tools do you recommend for those who have measured a rim?
See also:
- One users quest to diagnose uneven tire wear on the inside edge due to excessive and uneven alignment camber & toe (1) (2) & how one user selects a tire (1) & what are the most common bimmerfest tire recommendations (1) & where to buy your tires in the USA (1) & how many miles do you get per every 100 UTQG points (1) & recommended tire pressures (1) & the claimed benefits of nitrogen gas (1) what tire changing tools do you need to break the bead on the rim and set the bead back on the wheel when changing a tire at home (1) (2) (3) & where are the marks on the wheel and on the tire for proper tire match mounting and wheel balancing to eliminate vibration (1) & what tools do you need to balance a tire and rim at home to eliminate shimmy or vibration at speed (1) & how do you properly dispose of your old car tires (1) & how to measure wheel dimensions such as runout and eccentricity at home (1) & where to get bent or damaged wheel rims repaired (1) (2).
 

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Does anyone know if the BMW specification is referring to peak to peak runout values? Or is it first harmonic amplitude?
 
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