Low Pro Step

Been dragging a 51' Fontaine which tends to sit up higher than most steps and really screws me out of anything higher than 120-122" depending on weight. Was thinking of getting a low pro 53 tridem. Does anybody have any issues with 17.5s, albeit the drums are smaller and the tires are probably harder to find. Anybody have any issues with bottom clearances, keeping tires on em, etc. The reason for the tridem is potential customer who ships 50k equipment. Still would have to permit but I figured that three axles would carry the weight better than two, dunno...