How to Read Bicycle Tire Sizes

it always amazes me how many people I hear from who don't know what size their tire is and I say to them we'll just look at the tire the information is right there and they look and they can't see it can you see it it's right here see it right here right where I'm rubbing my thumb now the reason you can't see it is because it's molded into the tire and probably doesn't do a whole lot for marketing to have this blatantly displayed on the side let's move in on it just a little bit more here maybe if YouTube is good you can just start to see that raised print when they approach it from a different point of view and see if we can make this a little bit clearer okay let's go back to kindergarten here and see what this thing says you tried and true method since I probably can't get the light just right you can see this if you hold in the right light but it ain't going to happen here so let's do this this is fun innit it's like scratching a lottery ticket maybe it has now revealed its secrets and I'll read it for you in case you can't see it really well says 28 - 559 28th of the width of this tire 559 is the bead seat diameter also known as a 26 by 1.1 inch tire critical information here inflation pressure six to eight bars let's translate that into psi and we've got 85 215 pounds per square inch so this is pretty cool stuff here now let's look at some of this other stuff like what is a bead seat diameter and what is this width really mean we took the measurements of this tire it sets 28 millimeters wide let's see if that's really true let's take this caliper here brings it down here so you can see it a little bit better and measure this and see what we come up with whoa and ring 26.27 accuracy of this device is plus or minus 0.1 millimeters so this tire is considerably narrower than 28 turns out that this is an area where there's not a whole lot of standardization there's a ton of standardization in bead seat diameter because it's really critical but width really floats around it can be all over the place what exactly is a bead seat diameter well if I take this tire right here and I pull it away from the rim you can see this area right down in here it's very bottom part of the tire and there's a bead in there and that bead sits in the inside part of the rim here and keeps the tire in place when it's inflated so this diameter is known as the bead seat diameter just to make this a little bit clearer I kind of wrote in the numbers for you just to review the 28 was the width of the tire the 559 is the bead seat diameter BT diameter is kind of engraved in stone it's a hallowed number it conforms to an international standard it makes interchangeability among tires easy to predict and it makes it easy to buy the right tire for the right bicycle other numbers may be flaky but the bead seat diameter is not and then finally over here we had the pressure we headed up here in bars 14.7 pounds per square inch is equivalent to 1 ba R so that led us to 85 215 psi pressure for this particular tire what we're looking at here is a list of tire sizes from Sutherlands manual this is really cool this will make you appreciate tires here's the bead seat diameter here here's that ISO marking we'd looked at 622 is what we call a 700 C tire probably not what you would expect let's go down here and look at a few more here's a good one 584 or 571 both 26 inch this is this 571 is the popular 650 C tire 584 right above it is a 650 B it's a French size that's making a comeback you can get some really really nice tires in 584 these days come down a little bit further what's 559 well 559 is the mountain bike 26 inch variety of different widths here and tires quite a bit highly populated come down a little bit more what do we get to here here's 520 now this is the 24 inch size that we use on our terry bikes are very small road bikes and down here here's another 24 inch it's a 507 which is used on 24-inch off-road tyres mountain buy tires you could spend a lot of time just looking at this I mean there is some really great stuff here this is what I would call a geeks delight when it comes tires

Channel: Terry Bicycles

Views: 256,218

Rating: 4.0858145 out of 5

Keywords: tpb_Bicycle_Techniques, bicycle tire

Id: b5IubxlsTm8

Length: 5min 46sec (346 seconds)

Published: Wed Jul 28 2010