What Pulley ratio should i use for running bigger tires?

i recently aquired another gilson.

the rear tires are 26x12.00x12 V treads with lugs about 1/2 in big or more and the front tires are 18x9.50x8, the transaxle is a gear drive peerless 5 spd. what do y'all think the proper gearing would be? this thing sees mud and trails i don't need it fast or anything. it currently has 5 and 5 pulleys and im thinking thats a little bit to fast for transaxle to handle with these massive rear tires

1:2 or more properly .5 to 1 . bigger on the motor than on the tx. i have seen 5 speeds run 40 with 38" tires, but for a trail runner I wouldnt go more than 25. find out the gear ratio of the tx and run it through a gocart mph calculator. I could give the formula, but it is easier to do the auto calc. you will need tire size and gear ratio. you can change ratio to find the pulley you need for the speed you want. aim for too fast and you will run out of motor, aim too low is better, your tranny will last longer.

it seems like a 1 inch pulley would slip ALOT and i never heard of gear ratios like that would 5 and 5 be too fast or kill the transaxle?

on a size note the garage in your avatar looks familar are you the owner of a big jacked up gilson rolling V treads or am i thinking of someone else?

thats prbly me. The black '78 with a stack? I also have 2 pullers, red '74 and a silver'72

gear ratios are reduced to x to 1 so your 5 to 5 would be a 1:1, 10 to 5 would be a 2:1

yea it had a stack on it and a flapper i think... mind posting pics up since i have the same gilson?

also im confusing myself can you list a few pulley ratios instead of gear ratios? ha....

gear ratios and pulley ratios work the same. to find gear ratio on your transaxle, put it in high gear and rotate the input pulley until the axle makes 1 full revolution. the number of pulley turn is the first number. most are 6:1 to 10:1

here is a quick video of it in the mud pit

http://illiweb.com/fa/pbucket.gif4

that thing looks awesome mines actually similar only its an 80s and no lift. what pulleys are you running on that gilson? thats exactly want mine to work.

I think I used a 7 on the front and a 4 on the back. had to change out the motor to a 17 hp kohler single to get the big pulley on the front. I had to move the motor back about 3 inches. it was super slow stock, barely 5mph