Jeeps Canada - Jeep Forums - Driving on pure ice; best PSI

Jeeps Canada - Jeep Forums (https://www.jeepscanada.com/)

- Jeep Mailing List (https://www.jeepscanada.com/jeep-mailing-list-32/)

- - Driving on pure ice; best PSI (https://www.jeepscanada.com/jeep-mailing-list-32/driving-pure-ice%3B-best-psi-10411/)

Re: Driving on pure ice; best PSI

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:
>
> Ok, I want to get everyone's heated opinion on whether I should air
> down, and if so, how much, when I go out to race my jeep on a frozen
> lake this weekend.
>
> Mine is a 97 TJ with 4" of lift and 33x1250r15 BFG AT KO (brand new)
> tires, siped (yeah, I paid for the stupid siping that Discount Tire
> practically forces down your throat. I made him do it for half the
> price, though, at least ;-) )
>
> Anyway, I've heard equally strong opinions both for and against airing
> down for the race on the frozen lake. Some think I should, if
> anything, air up; presumably they think this will further reduce my
> contact patch, but give me more PSI at that contact patch to get
> traction. Others think I should air down to about 20 to 25 PSI (I
> regularly run at 35 PSI on the highway) in order to get more surface
> area of traction (albeit at a lower PSI at the contact patch).
>
> What do you all say to this? I know we've had this discussion with
> regard to inclement weather driving on roads, but never with the sole
> purpose of getting the best performance on nothing but an ice covered
> lake, with no regard for performance in any other situation...
>
> I'm currently leaning towards the airing down to 25 PSI idea...
>
> Thanks,
> Bob

Re: Driving on pure ice; best PSI

Roughly 1/23/04 14:55, Bob's monkeys randomly typed:

> Ok, I want to get everyone's heated opinion on whether I should air
> down, and if so, how much, when I go out to race my jeep on a frozen
> lake this weekend.

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.
>
> Mine is a 97 TJ with 4" of lift and 33x1250r15 BFG AT KO (brand new)
> tires, siped (yeah, I paid for the stupid siping that Discount Tire
> practically forces down your throat. I made him do it for half the
> price, though, at least ;-) )

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.
>
> Anyway, I've heard equally strong opinions both for and against airing
> down for the race on the frozen lake. Some think I should, if
> anything, air up; presumably they think this will further reduce my
> contact patch, but give me more PSI at that contact patch to get
> traction. Others think I should air down to about 20 to 25 PSI (I
> regularly run at 35 PSI on the highway) in order to get more surface
> area of traction (albeit at a lower PSI at the contact patch).

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.

>
> What do you all say to this? I know we've had this discussion with
> regard to inclement weather driving on roads, but never with the sole
> purpose of getting the best performance on nothing but an ice covered
> lake, with no regard for performance in any other situation...
>
> I'm currently leaning towards the airing down to 25 PSI idea...

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.

--
Now that Spirit Rover has confirmed the presence of weapons of
mass destruction on Mars, we are preparing to invade...

Re: Driving on pure ice; best PSI

"Bob" <magicclaw@mac.com> wrote in message
news:47b769ae.0401231455.f31f718@posting.google.co m...
> Ok, I want to get everyone's heated opinion on whether I should air
> down, and if so, how much, when I go out to race my jeep on a frozen
> lake this weekend.
>
> Mine is a 97 TJ with 4" of lift and 33x1250r15 BFG AT KO (brand new)
> tires, siped (yeah, I paid for the stupid siping that Discount Tire
> practically forces down your throat. I made him do it for half the
> price, though, at least ;-) )
>
> Anyway, I've heard equally strong opinions both for and against airing
> down for the race on the frozen lake. Some think I should, if
> anything, air up; presumably they think this will further reduce my
> contact patch, but give me more PSI at that contact patch to get
> traction. Others think I should air down to about 20 to 25 PSI (I
> regularly run at 35 PSI on the highway) in order to get more surface
> area of traction (albeit at a lower PSI at the contact patch).
>
> What do you all say to this? I know we've had this discussion with
> regard to inclement weather driving on roads, but never with the sole
> purpose of getting the best performance on nothing but an ice covered
> lake, with no regard for performance in any other situation...
>
> I'm currently leaning towards the airing down to 25 PSI idea...
>

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.

Re: Driving on pure ice; best PSI

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

"L0nD0t.$t0we11" <"L0nD0t.$t0we11"@ComcastDot.Net> wrote in message news:<X3kQb.132534$I06.1175142@attbi_s01>...
> Roughly 1/23/04 14:55, Bob's monkeys randomly typed:
>
> > Ok, I want to get everyone's heated opinion on whether I should air
> > down, and if so, how much, when I go out to race my jeep on a frozen
> > lake this weekend.
>
> 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.
> >
> > Mine is a 97 TJ with 4" of lift and 33x1250r15 BFG AT KO (brand new)
> > tires, siped (yeah, I paid for the stupid siping that Discount Tire
> > practically forces down your throat. I made him do it for half the
> > price, though, at least ;-) )
>
> 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.
> >
> > Anyway, I've heard equally strong opinions both for and against airing
> > down for the race on the frozen lake. Some think I should, if
> > anything, air up; presumably they think this will further reduce my
> > contact patch, but give me more PSI at that contact patch to get
> > traction. Others think I should air down to about 20 to 25 PSI (I
> > regularly run at 35 PSI on the highway) in order to get more surface
> > area of traction (albeit at a lower PSI at the contact patch).
>
> 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.
>
> >
> > What do you all say to this? I know we've had this discussion with
> > regard to inclement weather driving on roads, but never with the sole
> > purpose of getting the best performance on nothing but an ice covered
> > lake, with no regard for performance in any other situation...
> >
> > I'm currently leaning towards the airing down to 25 PSI idea...
>
> 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.