That... is an interesting subject!
The manual for my ST1032 (buried in the "dealer prep" section) says to inflate the tires to 20 PSI. I think in other literature for that machine (the service manual?) I've seen a recommendation of 14-20 without chains and 20 if you're using chains.
But... the tires (sno-hog type) that came with the machine, the xtracs I put on there, and the sno-hog type ones on my ST824 all say "max. 14 PSI" on the side!
So I inflate them to 14... but would love to know why the manuals call for more.
~1994 Ariens 924084 (ST1032) "papa bear": restored, re-engined, real nice!
1991 Ariens 924050 (ST824) "mama bear"
Toro PowerCurve 1800 "baby bear"
Be alert! America needs more lerts.