Whats the max height you would see on a conversion, I am getting ready to build a steel building and want to make sure that the door opening is tall enough?

That's hard to say, but the maximum legal height for a road going vehicle is 13'6" unless you have a permit. I doubt that many conversions are over 12 foot, but the exhaust may be at the 13'6" level.

....correct!.....geof kaye

glamis, mine is 12'-2 1/2" at the top of the satillite dome--- i've got a sign on my dash that says CLEAR-- 12' 4" i'd say if you could go 13' on the door or what ever the next increment over 12' 6" in door height from your door co. ya' don't have to open it all the way --- but i'm thinkin' that might be a better deal than jackin' the shop up OR lettin' the air out of the tires-----mase

......standard fire department/truck garage door is 14'...geof kaye

My new 32 foot Showhauler is 13' 4" tall I ordered the 6" higher ceilings and the truck is sitting on 22.5' tires.

In my buildings I have 16' eave height with 14' doors. That is about as small as you can go IMO.
Randy