Bob_Engelhardt
Freshman Member
Offline
I am SO frickin' frustrated!! I have been all over the web (it seems) trying to find an answer to a really simple, common knowledge, question: what is the metric size for TD tires? _Including_ aspect ratio!
Not finding it, I measured my old style tires (5.50 x 15 Mich. XZX inflated to 18 psi). The section width is 162 +- 3 mm. The outside diameter is 645 +- 6 mm. The inside diameter is 381mm (i.e., 15 * 25.4).
Aspect ratio is defined as height/width. And height is (OD - ID)/2. So:
Aspect ratio = ((645+-6 - 381)/2) / 162+-3
= 81 +- 3
Then the TD metric tire size is .... (wait for it):
165/80R15 !!
Of course I could be wrong and I would welcome corrections. Otherwise let this be a defining post for anyone else seeking his metric tire size.
Bob
Not finding it, I measured my old style tires (5.50 x 15 Mich. XZX inflated to 18 psi). The section width is 162 +- 3 mm. The outside diameter is 645 +- 6 mm. The inside diameter is 381mm (i.e., 15 * 25.4).
Aspect ratio is defined as height/width. And height is (OD - ID)/2. So:
Aspect ratio = ((645+-6 - 381)/2) / 162+-3
= 81 +- 3
Then the TD metric tire size is .... (wait for it):
165/80R15 !!
Of course I could be wrong and I would welcome corrections. Otherwise let this be a defining post for anyone else seeking his metric tire size.
Bob