Driving on pure ice; best PSI

Air up air down it does not matter ice is ice and the coefficient friction between the tires is the same. Chains or studded tires other wise you could be hosed but what do I know?

Nice tires, Bill.

The road-kill will be extra tenderized with those!!!

I keep my BFG 33x9.5 muds at street pressure, about 30 psi.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Bob wrote:

What are the rules for adding studs, spikes, etc. or is this gonna be a demolition derby on unstudded street tires? On street tires, after the first coupla cars, the ice will be covered with a snot-slick coating of ice and random water.

Airing down will keep the sipes and tread from adding roughly one toilet paper brake pad's worth of traction once the surface gets polished.

We always aired up, somewhat over street pressure, but the smart folks didn't race without at least studs. The really smart ones used spiked tires...and with those the ice may actually increase in traction over the course of the race.

The jet propulsion from taking a whizz out the driver's window will be pretty close to the difference of a 10 pound air up/down on non-studded tires. That tiny octupus whizz level of traction is best had by running near street pressure or just slight up, to keep the tread from deforming, so the sipes can work their futile attempts to keep the shiny side up.

Buy a set of sacrificial tires and pick up several dozen carbide bolts, 1 inch washers, 1 set of locknuts. Drill thru your treads, put a 1 inch washer inside and outside and use the locknut on the outside. Then coat the innards of your tires with rubber or contact cement over the bolts. Cut up one set of tubes and glue their outer half to the inside of the tread area to protect the actual tubes holding the pressure. It is much cheaper to buy spiked ice racing tires these days than to make your own in this manner. Probably more reliable too.

25 psi is not airing down. Airing down is setting the air pressure to about 15 psi. There is a strong argument that 25psi is the standard air pressure for your particular application.

OK, Well I'll just reply to all the people who posted responses to my original post.

I don't want to invest in this like some nut. I'm just going out and racing on an iced-over lake (Georgetown, CO) for the fun of it. (Something to do with my Jeep in the winter when the trails are all closed/snowed in.) The races are held in 4 different classes, from bare-rubber to cheater class (cheaters can have up to 1.5" bolts in their tires!). I am simply racing in the bare-rubber class, so we all have the same disadvantage of crappy traction. Several at the races had differing opinions about airing up, airing down, and how much to air up/air down for the races. I agree that 25 lbs is not "airing down" per se, this is just a level that one of the people at the ice races in a previous weekend suggested I bring the pressure down to for the races. Then I've got others saying I should air up, above my normal 35 lbs; so I just thought I'd see what the consensus (or at least the varied opinions) of this group would be.

So far, my experiences have been pretty terrible; my TJ doesn't want to follow the front wheels when I turn them...I got beaten by a friggin stock Ford Explorer last weekend. Of course, I realize that if I bought some tires specific for this, I would probably be much better off with some narrower tires. But again, I'm just doing this for fun; I can't afford two sets of tires and rims (nor do I have the room to store them), and I prefer the 33x1250s when wheeling in the summertime. Also, of course, this is the first year I've done this, so I'm sure driver ability is playing into this as well. But hey, I can at least try to get all the other variables taken care of first, right?

Any other suggestions BESIDES adding spikes or changing to a different set of tires, please post away! ;-)

Thanks, Bob

Drop to 2 wheel drive on the corners, then jump back to 4x4 for the power on the straights and engine braking control coming into the next corner, then drop to 2 wd to get around the corner. Then hit it back into 4x4 about 2/3 the way around the corner and pour on the power.

Jeeps are lousy taking ice corners at speed in 4x4. The wider the tire, the worse they are. Wide tires float rather than cut.

I even drop to 2 wd in the city when I have to turn left at an intersection in the snow, then same deal, about 2/3 the way around I drop back up to 4x4 and go.

Your tires are way too wide to have any decent ice traction, so I would just go out and play with the pressures to find the best bite. My guess is full street pressure or 35? you say you run. (You must have tough kidneys or really soft springs/shocks to run hard tires like that)

Could be 15 or 20 psi gives you a better grab depending on conditions, but I have good grab running hard (28 psi) on my tall skinny muds.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Bob wrote:

How about a couple of bags of sand on the front bumper - with a string back to the cab so you can release it on demand? My experience with

4WD > OK, Well I'll just reply to all the people who posted responses to my > original post.

LOL. I wish! Unfortunately I'm pretty sure that'd violate just a rule or two ;-)

Thanks for the ideas, guys. I had a feeling this was just going to be a crapshoot at best, but it was worth a shot there might be some holy grail answer (ok, not necessarily worth a shot, but what the hell?)

I did try to do the 4wd-2wd-4wd changing while driving in one of the practices last weekend, but it didn't do as well as I hoped. I'll try again this weekend. I probably need to get more practice timing the changes between 4 and 2 wheel drive.

And yes, Mike, I have kidneys of steel! lol

Switching in and out of 4HI should be completely seamless. There is no "timing" in this change. The gears are all going at the same speeds in 2HI and 4HI, so the change can easily be done literally at the flip of a switch. The Jeep doesn't use a switch to do this job, but it could.