I live on a 120 acre farm that has some steep fields that I mow. With areas that have wet weather springs that make things muddy and
slick, I need traction. I have what I think are R-1's which I think are also called ag
tires. The tires you call R-4's would not be good for field work,but
would be great if you must run a lot of pavement.
I used my U-5030 to bushhog some broom sage the other day on
hilly ground that was not at all dry. The tires did great when I did hit
a spot that was very wet from one of the springs in the field.
For me, I want all the traction I can get.
I have had no problem with the FEL with these tires. The only thing
is tire wear (R-1's compared to R-4's) if you used the FEL on pavement a lot. My tractor does
not see much pavement but it does see mud.
Good luck with what ever you decide on.
I know you will like the U-5030.