Cold and tires

[john zibell]

I've been commenting on this for years but it has mostly fallen on deaf ears. As temperatures drop, the properties of the rubber in tires changes to where it reaches the so called "glass point". This is a problem for cars, but even more so for motorcycle tires as traction is needed just to stay upright. I've advised folks not to ride when the temps drop below 30 degrees F but many said it wasn't a problem. Here is an article from Fox news that discusses the issue. foxnews.com/auto/dont-drive-winter-storm-tires-snowing

 

[Sempervee1]

True. In the cold tires lose pressure it seems also. I make it a habit to check the pressure on both our vehicles more often.

 

[john zibell]

True. In the cold tires lose pressure it seems also. I make it a habit to check the pressure on both our vehicles more often.

As temperatures drop, so does internal pressure. Basic physics. See aqua-calc.com/calculate/gas-pressure-and-temperature - This page relies on the ideal gas law, gas, and R is the ideal gas constant. Also to warm up tires, run a slightly lower pressure. The flexing of the tires generates heat. When I've participated in track days I drop pressure 2 to 4 PSI so the tires heat up and stick better.

 

[tris]

Very interesting John.
Especially as my reaction to seeing a drop in pressure when cold would have been to add air pressure back to that specified rather than reduce it as you recommend.
I understand the logic, but it's contrary to what I would have expected.
Something to consider none the less
Thanks

 

[GTM®]

To add .02 more cents, modern radials can run at what I (naively in my youth) considered absurdly low pressures and still work as designed for (traction). When I was racing in the '90s, extreme cold mornings predicated tire pressures as low as 19 psi. I would not hesitate to run modern radials down to 24~26 psi on super cold street rides. On the opposite side, modern track tires on the big hp bikes also are running 19 psi cold on the rear tire (on Seasonally warm/hot days), and 24 or so in the front... Counting on the ~10 psi gain when hot. They also will spin on the rim 4~6 inches per session, so they really should be rebalanced often. I feel as though this is a bit of a gimmicky trade-off for ignorant track day folks to consume tires. Pro level I get, but for track days seems silly to me.

 

[john zibell]

Very interesting John.
Especially as my reaction to seeing a drop in pressure when cold would have been to add air pressure back to that specified rather than reduce it as you recommend.
I understand the logic, but it's contrary to what I would have expected.
Something to consider none the less
Thanks

For street use I wouldn't drop pressure. Just don't ride in the cold temperatures if you don't have to. To me it isn't worth the addition risk of low available traction. The pressure is dropped a little for track use (not as low as Todd has done) to heat up the tires a little more. I attened a tire tech session presented by Bridgestone tire that stated when the core temp of the tire reaches 100 degrees C the tire would have max traction. Motorcycle manufactures tire pressure recommendations are a trade off betwee tire life, and available traction. The higher the pressure, the cooler the tire runs, but you then have less traction. Conversely if the pressure is too low, the tire gets hot and doesn't last as long. In addition if the pressure is too low, you may also encounter poor handling issues.

 

[DeadEye]

Not only do you suffer a pressure drop, but the colder it get the closer to hockey pucks that rubber becomes



FYI: regulation game-ready pucks involves mixing rubber and a bonding material and then placing them into a room-temperature mold to compress them.

 

[geebee]

Winter riding, they said it would be fun...

 

[Davy]

To add another variable, lower tyre pressures allow the tread grooves to close, limiting the tyres ability to shed snow, slush, water or any combination. My bike 1 day old. I rode the bike home. The main roads were okay, the side roads a little more interesting!

 

[Sempervee1]

Braver soul then me to do that in the snow.

 

[Nordicnorm]

50 km New Years day ride showing off the Griso's Christmas gifts: new alternator belt, repacked swing arm bearings, crash bars (donated by friend Steve last fall) and!! a brand new rear tire. 7 degrees C. Cornering with much care, keeping John Z's advise in mind. Home safe, didn't need the crash bars . Had our snow already, hopefully the last of it. HappyNewYear everyone. Winter in Scotland looks brutal!