Winter Cycling - how low is too low for psi

I have some 2.1 knobbies and i am getting more into riding in winter. I have a small commute on back roads (under 1 mile) 2 times a day. i know i should be lowering PSI for a bigger contact patch, so how low is too low?

I have some 2.1 knobbies and i am getting more into riding in winter. I have a small commute on back roads (under 1 mile) 2 times a day. i know i should be lowering PSI for a bigger contact patch, so how low is too low?

There is not a sound number that is too low. Your problem will be keeping the tire on the bead if you go too low. I run about 20 lbs in my tires and that is the lowest i would go. You can pretty much just give the sidewall a squeeze around the bead and see if there seems to be adequate pressure to keep it on the rim.

Some people actually glue the tire to the rim but I don't want to screw with that. I just make sure i have enough air pressure.

When you get snakebite it's too low :p .
-read the tire-it will probably have 2 numbers, stay above the lowest?

My 2.10 front xc tire reads 40-60 psi -250-400 kp.

I did it by feel 'psssssst' and I'm a light rider so I can probably go lower. I don't have a guage either.

Probably when we had ice roads, I was lower than 40, Lowest I remember the guage @ the gas station was 215 kp. And I may have pfffffffffffted some more .

snakebite and smashing the rim are the things to watch out for.

When the tire pressure is too low, the bike will feel squishy on a hard turn. This is especially apparent on my MTB.

Just to clarify...a "snakebite" is what happens if your tire pressure is too low and you hit a curb, pothole or other relatively sharp edge. The rim will smash into the pavement...well, it would but your poor tire is in the way. The two edges of the rim will leave two neat holes in your inner tube.

In my opinion, the traction advantage of low tire pressure is limited on the street, even a snowy one. I would prefer the more stable cornering and predictable behaviour afforded by higher tire pressure. I would stay over 30 or 35 psi, but that's just my preference. Experiment a little. On my MTB, I can loose the bead of my 2.25's under 30 psi, YRMV depending on your tire, rim, and weight. With wider rims, you can safely go to lower pressure, but mine are pretty narrow.

You do have to be careful with low pressure., On very bumpy ice I run 22 in the front ans 25 in the rear on my Nokian 296's. The lowest rating is 35 I think. I have been doing this for four years. Never a problem. On a very rocky trail in the summer I do the same thing with semi slicks.