I have a MX5200 with 12-16.5 R4 fronts and 17.5-24 R4 rears. I am disappointed in the traction, especially in 2wd. I currently have to operate in 4wd for about 80% of what I do. Can I replace the rears with 14.9-26 R1's and leave the front R4's on without messing up the ratio? I live in...