Impulse24.....You can change to whatever will fit, but it won't necessarily improve your ride or handling. Have you ever seen the guys who take a large car or half ton truck and put on 22" or 24" tires and wheels because they look cool. The problem is that the brakes were not designed to stop something that large. Just one issue, but probably not the biggest where you're concerned.
Rims are designed for a certain width tire so that the TIRE performs correctly. The tire manufacturer designs the tire to have a certain amount of flex and bulge for weight handing and ride. When you throw an oversized tire (width wise) on a rim, there is too much bulge. Your view that they are bolted and spaced by the rims and lug nuts doesn't make sense. If you put a wider tire on, it's going to hang farther over the rim. In some cases you wouldn't be able to even tighten the lug nuts because the tires would rub against each other. They're also spaced for cooling and to prevent pinching debris between them.
Your diesel was designed so that it sits at a certain height in the front and rear. This is why you have adjustable ride height valves. If you start messing with the ride height geometry, you'll suddenly realize that you'll have all types of issues,
There is a whole myriad of reasons a vehicle is designed with a certain tire and rim size. In the past 30 years RV's have become bigger and heavier....and the chassis manufacturers have increased the carrying capacity of tires and rims to meet the challenges of larger RV's.
Just because one company puts on 22.5 rims on their coach doesn't mean they're a better manufacturer. If you compare 22.5 tires through the entire 22.5 size range, there is a lot of difference in height and width, just like cars. Have you ever seen an aluminum 19 RV rim......no....so some manufacturers will go to 22.5 to dress up their wheels. The 22.5 tires on a gasser are much smaller in height and width than those on a 45000 pound DP.
This is not a hard concept to understand. You wouldn't put wheelbarrow tires on your motor home and you wouldn't put motor home tires on your wheelbarrow. Each vehicle is designed to ride on a certain size rim and tire. RV manufacturers go cheap on a lot of things, but rarely do you hear someone complain that they got too small a tire and wheel on their coach. Overloaded axles yes, tires and wheels....no.
