Why did we try double ply tire?
The higher the air pressure of tire is, the lower the rolling resistance
becomes.
But tire for mileage car will burst ,when air pressure is higher above
8kg/cm^2.
We confirmed that the double ply tire doesn't burst until it reaches
to very high pressure (15kgf/cm^2) by endurance test.
We thought that the double ply tire with very high pressure may achieve
lower rolling resistance than single ply tire.
簡易惰行試験結果
Test result of simple test.
3輪の内1輪のみを変更して比較した。
We changed one tire of three wheels.
2重タイヤの方が転がり抵抗が小さい。
The rolling resistance of double ply tire is lower than that of single
ply tire.
The rolling resistance of double ply tire is higher in proving ground!
Observation:
The surface of test road is different between simple test and the test
in proving ground.
In proving ground the surface of test course is rough.
And the surface in the simple test is very smooth.
So loss of energy by hysteresis of tire rubber may be different.