If you have a 2017 Casita
17 footer, you have plenty of room for 15" tires/wheels. I'm surprised you don't have 15" wheels already, but they are now standard on later model Casitas.
All you need to know to get the right wheels, (rims,) is:
15" diameter X 6" wide.
, (which means the rim is equally divided on both sides of the lug nut holes, inside to outside.)
The lug nut pattern is 5 Lug nuts on 4.5" centers
(And fwiw, the lug nuts on the standard Dexter #10 axle
, (which are what Casita
uses,) are 1/2" dia. X 20 threads per inch
If you decide to go with aluminum wheels, be sure to get the right lug nuts for them, because the steel rims use lug nuts with a different "shoulder" than the aluminum wheels use. And be sure that you ask for metal valve stems
for the rims, and also be sure to have the tires balanced
. This is important!
And as to tires, I recently upgraded, (last year,) to Good Year Endurance 225 X 15 ST, Load Range E tires, and I've been very happy with them.
And as to adding a bike rack, they do make ones that can be mounted on the front of the trailer, (over the propane
tanks,) or ones that you can insert into a custom made 2" frame mounted rear receiver hitch, but be forewarned that very few bike rack manufacturers will certify their mounts for use on the rear of travel trailers
, and the few that do exist are several hundred dollars. Caveat Emptor.