Quote:
Originally Posted by saltman
Does anyone know the outer diameter (or the circumference) of the 'tires' on 21" wheels? Same question for the 19" wheels.
|
Well, tire manufacturer is going to make this vary some but for the most part it will be 30" tall for a 21" tire, and 29" to 29¼" for the 19" tire.
Basically what you will do to find the roll-out is multiply the tire height X Pi
π which is 3.14159 to get your one-revolution roll-out. Then convert 5,280 which is feet per mile into inches and divide that number by the amount of your tire one revolution roll-out. Now you need to do the same for your 16" tire and see what the percentage of comparison is.
I will do the 21" tire for you.
30 X 3.1459 = 94.2477
5,280 X 12 = 63,360
63,360 ÷ 94.2477 = 672.271
Therefore your 21" tire will turn approximately 672 ¼ revolutions in a mile.
To be honest, I suspect a 650-16 tire will probably be very close to what a 19" tire will be (-around 29.250) so when I did the comparison for you, it comes out about 689 ½ revolutions. That only comes out to about 2½% difference between the two --or about 30 RPM. Not enough to make a difference. I would suggest you pull the engine and the flywheel down and balance everything. I suspect then you will find 50-555 mph much more obtainable.
.