Quick question,I have a 1978 CB550K,what are the equivalent metric sized replacement tire sizes for front and rear?
Thanks
The accurate answer is that there are none.
Inch size tires are 100% aspect ratio. Metrics don't often come that way.
A 3.25 front would be 86mm Height AND Width. A 90/90 is wider and shorter (90W, 81H) than the inch spec'd originals.
Stock rear is a 3.75 which is 95mm Height AND Width. A 100/90 tire is 5 mm wider and 5 mm shorter than stock specification.
It makes a difference in how the bike handles, and how the tire wears out (also changing the handling for the life of the tire).
You can still get Inch sized tires. But, the tire salesmen will try to sell you what they have in stock rather than order them for you. They'll make up all sorts of convincing arguments to sway your decision. Mostly just bull#$%*, as they don't know what they are talking about. They're salesmen not engineers. They have learned how to talk with authority. Kinda like politics.
The only issue is that a 3.75 rear isn't being made by good tire companies. However, going to a 4.00 rear still works really well.
Cheers,
