so I set the new tire next to old for size comparison
the new look somewhat larger and they are, but keep in mind, you are only realizing half the height increase of the new tire ( 1.5" over all, actual loss in fender well or frame .75" per side.
front side of old tire at frame extension
new tire in same position
new tire is closer, but the axle movement will swing the tire away from the frame a bit, if I hit something hard enough to cause the tire to go into the frame, I'm probably having more serious issues than this going on at the time.
right side fender well is a non issue, it's pretty tall, I can get my whole fist in there, maybe tall enough to set a 12oz beverage can on top of tire and still have clearance,
the left side, not so much, because of the slide out, the fender well tub is formed shallow, might have an inch of clearance, maybe 1.5" tops. I'll worry about it after this up coming trip, being as it's on the road center side, pot holes are less likely to be an issue. so I don't think normal road movement will be a problem for now.
as for sidewall clearance, no issue at all, plenty of room both sides of tire.
in the future, I will probably fabricate a 1-2" lift of some sort, possibly incorporate it to reach from side to side to also support the bottom of the fresh water tank, it bellies quite badly when full, I'd hate to have the tank fall out on the road while traveling. ( i won't travel with it full at this time for this reason )
the new tires are Kumho 857 Trailer tires, 185r14 Load Range D radial, 25.6" tall 1874 lbs ea capacity @ 65 PSI, and they have a speed rating of 99 mph ( you know we all wanna tow there !!)
Replacing the old (new) Kenda Karrier Load Star 175/85R13 radial LR-D 1610 lbs per tire @65psi, and 65mph speed rating.
these are for sale BTW if some one is interested, 2 on alloys ( 300miles, in the pic ) 2 never on the ground on steel wagons. wheels