sorting out tire sizing: inch versus metric

[MitchFav]

project bike is a 2 stroke JOG Venice style, just screaming for retro whitewall tires with some real tire tread. Bike currently has some modern style scooter tires that have very little tread (racing look, I guess, but too modern looking and too slick in the rain). They are 90/90 - 10. Narrowed down to getting the Shinko SR550 Whitewalls, but do I get the 3.0 x10 or the 3.5 x 10? This bike has drum brakes front and rear, articulated arm fork suspension, and I suspect it could take either size, but what is the vote of the experienced people on this forum, go with the narrower 3.0 or get a little extra road contact with the 3.5's? Also, the cheap tires on the bike now are tubeless, and I am finding mixed info on the Shinko SR550's as either 1) requiring tubes, or 2) tubeless, and at least one site said tubes or tubeless. So what is it? And if tubes or tubeless, which way to go?? The current stems are shot, so I could go either way and don't really have a preference, other than tubes are easier to fix if you have a puncture (no need to seal the tire, just patch or replace the tube, if the damage to the tire is small and easy to remove)

[rks]

If it were me, I'd go with the 3.50 x 10. I linked an old thread, with a chart that may help.

90mm = 3.54", so the 3.5 is much closer to the same width. The chart shows a 3.50 x 10 measuring .9" taller than a 90/90-10. This means it's 2.83" larger in circumference, or in other words, will cover 5.5% more ground, with each revolution. This means the scoot will be geared slightly higher....may not be a good thing on seep upgrades, but nice on flat ground.

The 3.00 x 10 is much closer to the 90/90-10 when it comes to overall height and circumference, but a half inch narrower. No change in gearing/performance, but may have a lower load rating.

Check out the link. http://scootdawg.proboards.com/thread/32533/tire-sizes

[MitchFav]

Well, with more research, I did figure out that the 3.0 x 10 is essentially the same as 90/90 - 10, and based on the overall diameter difference from the 3.0 to the 3.5, and the very tight clearance on the mud fender liner above the back wheel, have decided to stick with the 3.0 x10 , 90/90-10 size. But what I did find was that the Prima whitewalls were the better tire in the 3.0 x 10 size. They are tubeless, and have a smoother, but not slick tread compared to the Shinko's, so should be quieter at speed. With fresh, better quality rubber compound, these will be way better than the super cheap 12 year old tires that are on the bike right now. And look REALLY sharp after I paint the rims to match the pale blue metallic color of some of the body panels.