Topic: Should have made a new topic to start with- Tire question

[Ayrity]

I have a 76 cb550k, will this tire fit my rear wheel? it says its 4.00H-18  which i assume is 4inches across so 4in*25mm/in is 100mm which is the right rear wheel size right? I am just a bit confused first of all with all the switching back and forth on english and metric units tire sizes use (mm for width and in for rim size? stupid...) and also it seems they round the numbers of the widths quite a bit, a 3.25 in seems to me like it SHOULD be 82.5mm not 90...

[ev0lve]

http://www.webbikeworld.com/Motorcycle-tires/tire-data.htm

110/90 = 4.00/4.75
100/90 = 3.25/3.50

[TwoTired]

Why don't you just order the proper inch size tires?
Several manufacturers make the correct 3.25 x 19 front tire.  And 4.00x18 is pretty danged close to the correct 3.75x18 rear.
Locals don't like to stock the older inch size tires, as they don't move out the door as fast as metrics.  And they would rather get you something close in a metric size that they do stock and can sell you immediately.  The metric tires however, do not have the correct aspect ratio for the bikes frame geometry.  So, it is a compromise for which you pay for with "different" handling qualities for the 550, usually sacrificing the nice neutral, well mannered feel.  Salesmen don't care.  It's you that has to live with it.

They will order if you insist, and resist their "recommendations".