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Motorcycle Tire Size
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Topic: Motorcycle Tire Size (Read 2075 times)
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mbuk
Jr. Member
Posts: 48
Motorcycle Tire Size
«
on:
October 15, 2013, 01:24:17 PM »
Building a Kawasaki KR1S (250 production) for Bonneville and i am having trouble getting the original tyre size in V rating which is 140/60/18, but i can get 140/70/18. Will the higher profile tire be good or bad or not make much differance?.
140/60-18 140/70-18 Difference
Diameter inches (mm) 24.61 (625.2) 25.72 (653.2) 1.1 (28) 4.5%
Width inches (mm) 5.51 (140) 5.51 (140) 0 (0) 0%
Circum. inches (mm) 77.33 (1964.12) 80.79 (2052.09) 3.46 (87.96) 4.5%
Sidewall Height inches (mm) 3.31 (84) 3.86 (98) 0.55 (14) 16.7%
Revolutions per mile (km) 819.37 (509.13) 784.25 (487.31) -35.12 (-21.82) -4.3%
Thanks
Andrew Lewis
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sabat
Hero Member
Posts: 1539
Re: Motorcycle Tire Size
«
Reply #1 on:
October 15, 2013, 01:45:11 PM »
Hard to know exactly, but I would guess it won't make much difference, the speed rating is certainly more important in this case. Be sure to include an accurate circumference measure in your gearing calculation. good luck, Dean
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donpearsall
Sr. Member
Posts: 873
Re: Motorcycle Tire Size
«
Reply #2 on:
October 15, 2013, 02:19:01 PM »
Which Bonneville are you attending? Speedweek? BUB?
If BUB I asked the same question of Drew, the head AMA/FIM inspector and was told that with a production bike, it is allowed to change tire size if it is required to meet the speed requirements.
Don
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550 hp 2003 Suzuki Hayabusa Land Speed Racer
mbuk
Jr. Member
Posts: 48
Re: Motorcycle Tire Size
«
Reply #3 on:
October 15, 2013, 03:01:08 PM »
Hi, i will be attending Speedweek. i don't think there's an tech issue. It's more a performance question.
Andrew
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JonAmo
Full Member
Posts: 169
Re: Motorcycle Tire Size
«
Reply #4 on:
October 15, 2013, 07:28:03 PM »
Well I guess if you use the 140/60/18 "V" you can't race.... Use the 140/70/18 and in this case it doesn't matter what it does, because you now can race... Doesn't seem like too much of an decision to me?
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edinlr
Sr. Member
Posts: 344
Re: Motorcycle Tire Size
«
Reply #5 on:
October 24, 2013, 11:09:18 PM »
The 70 series tire should be slightly taller than the 60 series, so it will raise your gearing slightly (lower numerically). I have found there is often as much as a half inch height difference between the same size tires, but it is probably less than a one tooth change on your rear sprocket. Enjoy the safety of your new tire.
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Honda CX650 turbo, Kawasaki H2 Ninja, Kawasaki ZX750 turbo
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Motorcycle Tire Size