73jeep said:I think your 1250 was replaced by 1433 model(size,hp,etc.). The R4 Ind. tire used for the rear on the 1433 was a 15 x 19.5 tire. Not sure the size of the front tire, but maybe someone here on the forum may have a 1433 with R4 tires & be able to help.
On a 1250 and 1260 there was 2 r4 tire options:
Front 25x8.50-14 Rear 15-19.5
or
Front 10-16.5 Rear 14.9-24
Try to match your front and rear tires to get a 0 - 5% lead.. That means the fronts will be turning 0 - 5% faster than the rears. Here is a formula to help calculate this.
(Front tire loaded radius/Rear tire loaded radius X axle ratio) -1 X 100 = % lead.
A tire dealer can give you the tire info and the axle ratio for a 1250 is 1:1.6077771. This means that the front axle spins 1.6077771 times for every 1 time of the rear axle.
Hope that helps.