Ideal tyre (tire) temps.

Does anyone know what the ideal temperatures are for m/c tyres for
racing purposes?
Does it vary Dependant on brand/construction?
Can it be measured with an electronic surface temp probe adapter thingo
for a multimeter? Or do you need a specific tyre temp gauge (gage - for
the Yanks/Mercans)?
What temp. do tyre warmers operate at?

All these questions?
Bummers

 

Motorsickle tahrs. Them's those round black donuts what keeps yer
chromed rims from getting all scratched up, right? ;-)

Street tires will optimally run from 122 to 158 degrees F. Race tires
will run from 175 to 250 degrees F. Some manufacturers are supplying
"green" rubber to the racers. "Green" rubber isn't completely cured at
the factory, it's still soft and weak. But it sticks to the track well.
The rider is actually curing the tire as he rides his warm up laps and
the first race laps. When he feels the tire "come in", it has the most
traction it's ever going to have. He can get onto the power early at
higher lean angles. Now he can race competitively as long as the tire
lets him put all his power to the ground.

When he feels the tire "go off" it has less traction, he can't use the
throttle while leaned over. Then the special oils used to extend the
dynamic range of flexibility of the rubber in the tire begin to rise to
the surface. The tire feels greasy. If you examine a tire that been
through a few heat cycles and has cooled off, it looks blue, and it is
done for, as far as racing goes. Sell it to a squid so he can brag to
his buddies that he'd chewed up the tire like that on a race track the
previous weekend...

If you don't believe there is any oil in your tires, google up
"extender oil +cold process rubber"...

Sure. All manufacturers have proprietary rubber compounding "secrets"
but they are all experts, and they can figure out what the other guy is
mixing in his rubber kettle and duplicate it if the other guy's tires
are winning more races.

They all have their own ideas about carcass flexibility in the
crown and sidewall areas of the tire, too...

Riders expect the crown of the tire (the area underneath the tread) to
have uniform stiffness at all lean angles for consistent feel.

(But pointy triangular race track tires will have a different feel at
small lean angles, or straight up, than they feel while leaned over,
that's why you see riders stick a knee out and then scramble over to
the wrong side of their machine before turning into a corner.)

The sidewalls of different tires are taller or shorter, and they are
stiffer or more flexible according to the weight of the motorbike and
the way it's intended to be ridden and how rigid the chassis is when it
hits bumps while leaned over to the max...

The suspension engineers are using the sidewalls as a rubber spring to
absorb those out-of-plane bumps that the suspension system can't
handle. The out-of-plane suspension load problem is so bad that chassis
engineers keep redesigning their chasses to be less rigid. You may hear
that the latest Honda chassis has been "improved" in terms of torsional
rigidity, but they are saying which direction they are "improving" it
in, more rigid, or more flexible...

Then there's the weight business vs. responsive turn-in
characteristics. Bigger 4-stroke motorcycles can be porkers in terms of
weight, but the riders still want agile handling out of their
elephant-on-wheels. The engineers have been building bigger, more
powerful motorbikes for decades, giving us great big rear tires that
can handle the power without overheating themselves and melting, but
the tiny front tire looks like it belongs on a motorscooter...

That front tire has to have a very rigid sidewall in order to support
the front end of some porky literbike that might weigh 750 pounds with
a 250-pound rider that has a 46 inch waistline. This rider sits around
in a cubicle at work, typing to internet newsgroups all day, drinking
coffee and eating donuts, and when he goes out on his Holy Track Day,
he expects that motorscooter tire on the front of his Hiya Buzzard to
hold his engine off the ground while he does terrible things to it, and
maybe he even complains about how fast it wears out and how harsh that
poor overworked tire rides when he's on a freeway. Jeez!

Sammler motorbikes are so much more gentle on their tires, the American
Motorcyclist Association has made 600cc the displacement limit for
their
Formula Extreme class that replaces the old 1000cc class in US
superbike racing...

Tire temperatures are measured with a device called a "pyrometer". Car
tire
temperatures will vary from edge to center to opposite edge and can be
interpreted as to optimum pressure and whether the camber and toe-in is
set right...

But motorbikes run on one side of their tires more than on the other,
and the less used side may be too cold to produce optimum traction
while the other side is overheated and getting "greasy" feeling...

Probably 175 degrees and up...

 

Many thanks kk,
Bummers
Think you answered tyre questions I had yet to ask.

 

I found another - how quickly do the tyre temperatures drop?
If it takes 1 min. to get from track to pit lane before measuring tyre
temp - do I need to make an allowance for the drop off before measuring?

 

Check out this Bridgestone .pdf file. It's very instructive even though
it dates back 20 years...

mc.bridgestone.co.jp/pdf/mcintroe.pdf

If you're planning to go motorbike racing, get used to going to your
local race track every race weekend and hang around the paddock talking
to everybody that races in the class you're going to be riding in. If
you listen to people and don't try to impress them with what you know,
they will open up and tell you everything....

Don't expect the class champion do do that, he needs to keep some speed
secrets to himself so he can keep winning. But a lot of the guys just
want to compete and ride close to each other and ride hard and it's
amazing how much they will tell you if you act humble and just listen
instead of beating your own drum...

And, when you go to the race tracks, hang around the tire distributors'
trucks and ask questions about what the popular tires are this season.
They will usually have a chalkboard with all the recommended tire
pressures for the most popular tires...

 

It'll be from a compatible era of when I raced last!

 

I realize everyone is talking about pressures/temps for track use,
but I think it bears noting: street pressures should always be
higher, esp. on front wheels, to protect the rim against deforming.
City streets bite, and none are worse than ours in San Francisco.

On a reliable, smooth surface like a track, I prefer the lowest
pressure possible without squirm. This tends to reduce warm up
time and increase the size of the contact patch. But this will
depend on how compliant your suspension is, too.

 

Michael,
You may have meant a smooth *street* surface like a track but if
pressures are "just above squirm" won't they overheat easily & not
provide max. traction?
Bummers