G1 slips drive belt now

[Tom's Toy]

Got a G1 about a month ago. It runs good. I have a farm with cattle. It had smooth tread tires on it when I got it. Keep spinning out on hills. I have a Honda four wheeler so this is just a new toy to play with. Ordered some 20 x10 x8 inch tires and steel wheels. Got them today and put them on. Took the wife out with me see some new calves. We were stopped and tried to take off going up a small hill and the main drive belt started to slip eased into and I got it to move but if I would floor it I could get it to slip. With the new tires there is no spin,the old tires would just spin. So do I need a new belt?Out earlier just me it did fine. The tapered cone on the drive is worn a little secondary looks good. How wide is the drive belt? Is one type belt better then another? Thanks

[Spicyunicorn]

If drive belt is 1" wide or less it needs to be replaced

[Tom's Toy]

Thank you
I will check today. Before I put the rough tires on I guess the tires just spun. Cart runs pretty good top spend is 18 mph now, when up one mph with the larger tires. was hoping for 20 mph I . Might try drilling out the governor arm

[Spicyunicorn]

Also probably wouldn't hurt to clean and inspect the drive clutch make sure all the weights are good just use a dry lithium lube so future dust doesn't collect in the clutch

[Tom's Toy]

Measured the belt 1 1/8 wide. Is it possible for the belt to stretch? The top inside edge of the belt is not really frayed but not exactly smooth. The sides of the belt seem good not glazed. It really is not a problem yet just wondered. The belt I know has to be loose. I can push the belt down between the pulleys to around 2" give or take,before I start to move the secondary clutch.
Earlier just fooling with it jacked up in the rear with it running looked like everything was working ok. It would raise the belt all the way to the top on the drive side when opened up.