[oldman3]

Dongray, please don't take this the wrong way. I just want to point out a few things, based on my own use.

#1. Don't know your wheel size, but a 185/75/15 is 24.97" tall, lets call it 25"
a 225/75/15" tire is 28.05" tall lets call it 28" (based on my Cooper tire
book). 25" divided by half is 12.5" and 28" divided by half is 14". 14"
minus 12.5" equal 1.5". This is how much it will raise the distance from
I-beam to the ground.

#2. You talked about scrub line. The picture of you front end can be taken
at a angle, and I may be completely wrong. But if you take a straight
edge, and go bottom of wheel to bottom of wheel, you axle would be
right on the ground (remember I may be wrong). If this is true the only
way to change scrub line is to go to a larger wheel diameter wheel. A
16" wheel would give you and additional 1/2" clearance.

Hope I didn't step on any toes, just don't want you buying new tires and then find out you need different wheels...Jim