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ContiClassicAttack actual dimensions

2324 Views 36 Replies 7 Participants Last post by  crazypj
I am building a cafe racer with a combination fork brace/fender mount/caliper hanger. I need to know tire dimensions/clearances to complete this part of the project, but don't want to actually purchase the tires until the project is closer to completion, so the tires are fresh. (I've been "working" on this bike for nigh on 30 years, and it might be a couple more years before it's actually ready for tires.) Since no tire company other than Avon seems to publish actual measurements of their tires, I was hoping someone here could take a couple of measurements for me. The bike has an 18 x 2.15 Sun rim on the front. At this point, I am considering the 90/90 R 18 ContiClassicAttack and the Michelin 100/90-18 Pilot Activ. If anyone out there has either of these tires and can measure the actual overall diameter and width, I would greatly appreciate it. Thanks.
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Just how close are you trying to build it that the Avon numbers would not work? Or are they for a completely different profile tire.

When it has a profile number like 90
  • 90 = aspect ratio (cross-section height is 90% of width)
If it has no profile number cross-section height is 100% of width
That's a V rated tire, it's capable of 150 mph, they get bigger in outside diameter when you spin the up fast, might want to keep that in mind when you consider clearances, it trips up a lot of people.
Centrifugal force is amazing stuff, watch the shape of the tire change here:

Imagine goodyear trying to give you outside dimensions for that tire.
You should be considering radials because they are far better then bias ply tires.
Measure the circumference with a length of string, divide the circumference by π (3.14)
That's your diameter.
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