Weaving doesn't help warm tires
Posted over at the ZX-10.net forum:
Weaving Makes For Good Collisions By Dave Swarts
Weaving to warm tires is a fiction that just won't die. All sorts of
riders who should know better can be seen weaving wildly on warm-up
laps, and we've seen plenty of collisions and near-misses caused by one
guy weaving into another guy on a warm-up lap. Yet some riders persist
in the belief that weaving actually does something other than create a
hazard. So, since we had gathered a test bike, a test rider, all sorts
of measuring instruments, some extra tires, and had a track to ourselves
for our big tire test (Roadracing World, January, 2000), we decided to
test the effects of weaving on motorcycle tire temperatures.
We conducted this experiment using Mark Junge and his 1999 Kawasaki
ZX-6R, at Oak Hill Raceway. Michelin tires were used for this test, the
front a standard Pilot Race, and a Pilot Race "W" on the rear. First, we
measured the cold tires' core temperature in the middle and on both
sides of the tread, front and rear. We then sent Junge onto the track to
ride slowly in a straight line and then measured the tire temperatures.
Then we instructed Junge to weave aggressively from turn eight to turn
two and back again (approximately one-half mile), and measured the tire
temperatures again to see how much heat was produced in the tires.
Next, we let the Michelins cool off. We then heated the tires on warmers
for 45 minutes per Michelin's recommendation and took the tire
temperatures. Then Junge went out and did the same weaving and
temperatures were taken again to see if additional heat was built up or
if heat was lost.
Next, Junge was sent on a standard warm-up lap. We then quickly measured
the tire temperatures. Then Junge did another 1.8-mile warm-up lap, this
time weaving, and we measured the temperatures again to see if weaving
built additional heat when compared to a standard warm-up lap, kept the
heat in, or lost the heat. Then we did the half-mile of weaving again
before taking the tire temperatures yet another time.
To complete our test of tires and temperatures, we sent our rider out on
two normal warm-up laps. Once back on the starting grid, we stopped the
bike with the tires remaining on the pavement just as you would sit on a
grid with the 3-minute board in the air. Then we measured each tire, as
quickly as possible, to see how quickly the tires lost the heat built up
on the warm-up lap.
The first thing that we discovered while trying to take the temperature
of the cold tires was that the sun has a significant effect on a tire's
temperature. Our test bike was under a canopy but the front tire was
still in direct sunlight on an 88-degree, Texas afternoon. Just from
sitting in the sun, the front tire had between 10 to 20 degrees more
heat at the tread's core, not the surface.
When Junge rode in a straight line at line at approximately 40 mph for
about a half-mile, the shoulder of the tire that was in the shade
remained at 85-88 degrees F. The temperature at the center of the tires
went up slightly while the shoulder of the tire facing the sun also
started picking up heat. Then our rider went on his weaving course and
came back. Once again the side of the tire facing away from the sun and
the center changed very little. The side of the tire facing the sun
continued to gain heat. We attributed this solely to the sun as Junge
was careful to weave equally hard on each side of the tires.
Junge went back to his task of learning Oak Hill on his "A-bike" while
we took the weaving test bike back under the canopy and applied Tyr Sox
tire warmers for 45 minutes. After the warmers, the rear tire had about
129 degrees F across its entire tread while the front held 171 degrees F
on the right, 175 degrees F on the left, and 182.4 degrees F in the
center. Both warmers were on for the equal amounts of time.
Just as I was organizing a theory into how the tire warmers have equal
heating elements but the (120) front tire has less surface than the
(180) rear tire, I noticed that the bike had been put back in its
original parking spot with the front wheel in the sun. Although I can't
rule out my equal tire warmers versus different-sized tires theory, I
can't rule out that the strong sunlight increased the effect of the
As soon as we took the post-warmer temperatures, Junge went out to do
the same exact weaving course. The right/away-from-the-sun side of the
rear tire lost 12 degrees of heat. The right side of the front lost 45
degrees. The center of the rear lost 5 degrees of heat. The center of
the front lost 43 degrees. The left side of the rear tire that was
facing the sun stayed steady at 129 degrees while the left front only
lost 36 degrees. Once again weaving did not build or hold the
temperature. The sun had more effect than weaving.
As soon as these temperatures were taken, Junge was sent off to do a
normal hot lap on the twisty, 1.8-mile course. After the hot lap, the
heat in the rear remained fairly constant, cooling just a few degrees.
The front continued to steadily lose its significant tire warmer heat.
However, the left sides of the tires were the warmest parts. We could
not attribute this to the sun because throughout our two-day test, tires
always recorded higher temperatures on their left sides after doing any
laps at speed on the track.
Then, we sent Junge to do an entire lap of weaving. Again, the weaving
failed to hold heat anywhere on the tire. Then Junge once again did his
straight weaving test, and the tires began cooling rapidly. In fact,
during weaving the tires lost heat as rapidly or more rapidly as just
For our final test, we sent Junge out to do two laps to get some heat in
the tires. Then as the bike stood still on the racing surface just as it
would on a grid, we measured how quickly the tires lost their heat. I
had originally hoped to measure the six spots on the tires every 10-15
seconds. That proved too ambitious. I ended up measuring each spot every
45-60 seconds. Next time, I'll have two pyrometers. This was very
interesting, though. While the center and right sides of the tires lost
10-12 degrees over a 4-minute time period, the left side of the rear
lost very little heat and the front gained heat from the direct
Here are some conclusions. Tire warmers will produce the highest
pre-race tire temperatures. During the tire comparison test consisting
of 8-10 laps at 100 percent speed, we sometimes did not record
temperatures higher then straight off the warmers. So the best way to
warm tires is to use tire warmers.
The second-best way to warm tires is to take a hot lap. As powerful as
the sun proved to be, a good hot lap produced more heat than time in the
strong sun, and it's quicker, too.
The third-best way to warm tires is to leave the tires in strong, direct
sunlight. Just don't forget to get both sides.
But weaving, no matter how aggressive your lean angle and your speed or
how long the distance covered, does not build any additional heat in a
So now, we will hopefully never see another unfortunate accident from
useless weaving on a starting grid or pit lane. Case closed.
Comparison Of Tire Temperatures As Affected By
Warming Methods And Ambient Conditions
Ambient Conditions And Temp Probe Location In
---------Sun Rear--Left In Sun Rear--Center In Shade Rear--Right In Sun
Front--Left In Sun Front--Center In Shade Front--Right Warming Method
Cold Tire ------------85-- 87-- 86-- 94-- 105- 98
Straight line, slow --89 --98-- 85-- 95-- 106- 87
Weave aggressively ---96 --99 --87-- 99-- 104- 88
Tire warmers--------- 129 -130- 127- 176- 182- 171
Warmers and weaving --130- 129- 115- 139- 139- 126
Std. warm-up lap -----124- 122- 122- 130- 126- 120
Weave, 1.8 mile ------121- 118- 120- 129- 117- 119
Weave, 0.5 mile ------118- 115- 110- 114- 109- 113
Comparison Of Tire Temperatures As Affected By
Time On Grid And Ambient Conditions
Start Temp -----------128.6- 123.6- 120.8- 129.0- 116.4- 111.6
+0:45 seconds on grid 127.6- 117.0- 115.4- 128.6- 115.6- 110.6
+ 1:45 seconds on grid 126.8- 116.0- 114.6- 128.2- 113.6- 110.6
+2:45 seconds on grid 125.4- 115.0- 112.0- 127.2- 113.6- 106.0
+3:45 seconds on grid 124.0- 111.8- 108.2- 125.6- 113.0- 104.8
All temperatures in Fahrenheit. Track temperature was 86 degrees;
ambient temp in shade was 88 degrees. Cold tire pressure was 30 psi in
front, 28 psi rear. Tests were conducted on Michelin Pilot Race tires.
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