they quit giving the dimensions of the belts a long time ago. Deere did as well. They found out that if people have the dimensions, they could run down to napa and get a dirt cheap belt (and it is just that, cheap quality included) rather than the better quality/longer lasting oem belt. The OEM belt is specifically made for the usage, unlike most of the cheap "replacements". Marketing team said quit giving out the dimensions....let's get people to come to the dealer. I can't blame them.
If you have a T1570 you need one K1122-26130 (that's the hst belt aka drive belt). Then the deck belt (goes around all the deck pulleys) is K5112-71420 and finally the deck DRIVE belt (engine to deck) is K5112-51310
keep in mind that the T1570A may have different belt numbers than the T1570 so double check your model/serial number.
They list the belts in different areas. The hst belt is listed with the tractor. The deck and deck drive belts are listed with the mower. The mower deck is found in "option model" which is at the bottom of the page, LH side, and there are different decks available for the T1570 so make sure you get the model/serial off of the mowing deck to verify which deck you have.
if you are replacing belts, I'd HIGHLY suggest addressing the idlers too, particularly the hst belt idlers. They have a tendency to fail over time. Generally speaking I encourage everyone to replace the idlers while doing the belt, so you don't have to climb back underneath and do it again in just a few hours use.
