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Alex · September 29th, 2008, 02:57 PM

Hi Alex -

There used to be a very significant difference between radial and bias-ply tires. Their differing construction (one with plys that go lengthwise around the tire, the other that go perpendicular to the tire), meant that the tire profile and the strength of the sidewalls were very different.

What that difference also meant was that it was never recommended to mix radial and bias-ply tires on the same bike, and also, bikes designed for one type shouldn't use another type. Radial tires very quickly became known as the higher-performing, higher-spec type of tire, and much of tire development went down that path.

But, for particularly narrow tires (like on our ninjette), it turns out that some of the advantages of radial tires aren't as compelling. And in fact most of the tires that fit our rims aren't using radial construction. But the good news is that the tire compounds themselves aren't terribly different anymore, so a modern bias-ply tire in the correct sizes for our bike can perform quite well in both performance and tire life. People using the ninjette on the track swear by bias-play GT-501's, for example (though perhaps not the OEM version of the 501''s that came with some of our bikes).

What is never recommended is using a different size tire on a rim that wasn't designed for a larger tire. What happens in that case is the sidewalls are squeezed together more than the tire manufacturer intended, which can significantly change the profile (shape) of the tire itself. What tends to happen is that it gets much more sharply pointed, which causes accelerated wear. And when the bike is leaned over, the expected amount of contact with the road can be much less because the shape at full lean is different than was intended. There are problems putting smaller tires than designed as well, with a potential change in tire shape, but also a chance that the beads won't seal properly to hold air in well long-term.

Now folks have gone up a size in the past without the sky falling, but I'd be wary of any claims of improved performance. More than likely performance was the same at best, and likely a little worse than the stock sizes. But a larger tire does look a little better, I guess.

September 29th, 2008, 02:57 PM	#2
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	Hi Alex - There used to be a very significant difference between radial and bias-ply tires. Their differing construction (one with plys that go lengthwise around the tire, the other that go perpendicular to the tire), meant that the tire profile and the strength of the sidewalls were very different. What that difference also meant was that it was never recommended to mix radial and bias-ply tires on the same bike, and also, bikes designed for one type shouldn't use another type. Radial tires very quickly became known as the higher-performing, higher-spec type of tire, and much of tire development went down that path. But, for particularly narrow tires (like on our ninjette), it turns out that some of the advantages of radial tires aren't as compelling. And in fact most of the tires that fit our rims aren't using radial construction. But the good news is that the tire compounds themselves aren't terribly different anymore, so a modern bias-ply tire in the correct sizes for our bike can perform quite well in both performance and tire life. People using the ninjette on the track swear by bias-play GT-501's, for example (though perhaps not the OEM version of the 501''s that came with some of our bikes). What is never recommended is using a different size tire on a rim that wasn't designed for a larger tire. What happens in that case is the sidewalls are squeezed together more than the tire manufacturer intended, which can significantly change the profile (shape) of the tire itself. What tends to happen is that it gets much more sharply pointed, which causes accelerated wear. And when the bike is leaned over, the expected amount of contact with the road can be much less because the shape at full lean is different than was intended. There are problems putting smaller tires than designed as well, with a potential change in tire shape, but also a chance that the beads won't seal properly to hold air in well long-term. Now folks have gone up a size in the past without the sky falling, but I'd be wary of any claims of improved performance. More than likely performance was the same at best, and likely a little worse than the stock sizes. But a larger tire does look a little better, I guess. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)