fechter said:
I see Shinko makes a SR241 tire in 3.50-19 size. Does anybody know if this will fit in the rear? The next smallest size is a 2.75-19 which I'm sure would fit both front and rear.
Honestly, I think the best tire would be a Shinko 241 3.000-18" for the rear. The 3.50" tires are way too big and heavy.
I run a shinko 241 3.00 in 17" on my Q76R hub motor bike, and the tire is very good, probably the best for a hub motor ebike, its way fat enough and is not too heavy with a super soft tread compound and thick knobs. From what I heard when you go up to the 3.5" size you are adding like double the weight of a 3.0" tire. I think Rix told me that the 3.5" tires get too big and heavy. I see no reason why anyone would want bigger than a 3.0" tire. A 3.0" tire will run about 5 lbs, a 3.5" tire about 10lbs, but I could be wrong here as I never weighed the 3.5", but that is what I was told.
Here are the outer diamter of the shinko 241 tires.
2.75-19 = 25.16" This is probably close to the stock tires on the Sur-Ron
3.00-18 = 24.69" This is close to the 19" tires the sur-ron comes with so it won't affect geometry that much.
3.50-19 = 26.57" This is way bigger than the stock 19"
As you can see, the 3.00-18" is a very good size to keep it close to the stock tire, it is still light weight at around 4 or 5 lbs, it is a very fat tire. I love this tire at 17" on my Q76R. Compared to the tread on the 2.75-19" shinko 241, the 3.00 inch is super soft, and molds very easily to the ground with our light bikes. I have and ran both the 2.75-19" and 3.00"-17", the 3.00" version of the tire is way better. The 2.75-19" is very stiff and hard, not good for a light ebike.
I run my 3.00" shinko at 11-14PSI.
Of course you would only want this on the rear of the bike and not the front. It also doesn't matter if you use 18" rims on the rear, most dirtbikes use different size rims on front vs rear.
Here is the webpage for all these specs. Click on show advanced specs.
https://www.shinkotireusa.com/product/sr241-series/211922