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Tire size conversion

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Would anyone be so kind as to explain how to convert the old tire sizes to the new metric sizes :thumbsup: . For example, the rear of my 1980 Suzuki PE250 is a 4.50-18. What confuses me is the dual designation, ie 110/100-18 or 80/100-21 .

Thanks!!!!

Marc in Indy :ride:

1980 Suzuki PE250

2000 ATK 250LQ

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Would anyone be so kind as to explain how to convert the old tire sizes to the new metric sizes :thumbsup: . For example, the rear of my 1980 Suzuki PE250 is a 4.50-18. What confuses me is the dual designation, ie 110/100-18 or 80/100-21 .

It's 110/100-18 is supposed to mean that the tire is 110mm wide. The Height is 100% of the width, and the inside is 18 inches. So if you convert from mm to inches 110mm is about 4.33. More or less the same as the 4.5. It varies between manufacturers. A Dunlop 110/100-18 is close to the same size as a Maxxis IT 120/100-18. I don't know about the PE250, but I wouldn't go any wider than a Dunlop 110/100 or a Maxxis 120/100. A little narrow is fine. To wide and it is unusable because it rubs.

the 80/100-21 is the same as your basic 3.00-18 front tire.

If you think the dirt tires are bad, try getting a tire for an old street bike. I used a conversion chart and still got the wrong size! The tire ended up being too big.

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