[Angrysheep]

so the total diameter difference between the stock d220's and the 120/70 roadsmarts i installed is 0.63 inches. thats 16mm. so do i just raise the forks 16mm to mantain the stock geometry, or is there some witchcraft involved that i'm not aware of? thanks in advance

 

[slattmattery]

You would only raise the forks by the difference in the radius, not the diameter. So 8mm.

 

[Angrysheep]

awesome, thats what i was wondering. that makes sense. thank you very much.

 

[eddiemon]

You would only raise the forks by the difference in the radius, not the diameter. So 8mm.

+1

 

[Veee]

so the total diameter difference between the stock d220's and the 120/70 roadsmarts i installed is 0.63 inches. thats 16mm. so do i just raise the forks 16mm to mantain the stock geometry, or is there some witchcraft involved that i'm not aware of? thanks in advance

funny, according to Andy and some other experts that is not correct. he say it is 24mm.;D
http://forum.svrider.com/showpost.php?p=1385592&postcount=12

 

[Angrysheep]

yea, thats why i went straight to dunlop to get my specs.

120/60-17 d220 diameter 22.99in, width 4.49in
120/70-17 roadsmart diameter 23.62in, width 4.65in

 

[Veee]

yea, thats why i went straight to dunlop to get my specs.

120/60-17 d220 diameter 22.99in, width 4.49in
120/70-17 roadsmart diameter 23.62in, width 4.65in

they claim different width, how is that possible when both are 120?
btw. I would not trust their numbers either. trust tape measure.
usually I put wheel down on flat and put 2 squares against tires and measure in between to get diameter. before I take old tire and after I put new one on. you can also record new tire size for future so you know exact size when it was new. in case you really care about couple mm that wears out.