Another Tire question

[Hoakieman]

My '09 2500 cummins, crew cab, 4wd, came with LT285/60R20 tires. My wife is very short legged, I have a set of 18" rims. Will this lower the truck enough for her to get in, what size tire should I get to get it lower and what will this do to the ride. I'm not tire savy, but the cummins is very heavy and I know I'll need tires to handle the weight. I have to use a two step stool for her to get into the truck. I really appreciate any help with this.
Hoakieman
4th Gen, '09 crewcab, 4wd, automatic, stock

 

[John Jensen]

The rim size won't lower the truck. The factory tire size is 33" regardless of rim size. Suggest a set of side steps, bar or running board.

 

[mikeru]

I don't know if you can get them for your '09, but powered side steps work best for shorter people. They drop down lower and sit out farther than any fixed steps. And they stow away and don't stick out when you're driving like fixed steps do.