16.5 Slicks

[Rada]

Can someone explain the deal with 16.5" race tires? Not that I'm looking for any. I'm just wondering what the heck that 1/2" smaller wheel diameter amounts to. From what I could find it sounds like a big pain in the ass to run 16.5" rubber. There must be some good reason.

[hondarider102]

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Weight would be my best guess but I could be totally wrong here, I'm also curious to see what others have to say

[csmutty]

Drops the front end and puts more weight on it for better traction and feel.

[Kitt]

Drops the front end and puts more weight on it for better traction and feel.

what he's referring to is placebo effect

[CBR929RE]

gotta be a reason for it since its been the choice for pro teams for years. Its the only size MotoGP can run according to the rules.

[backinthesaddle]

Someone around here has a Desmosedici RR and I think that bike has a 16.5 rear tire making for an even more limited street tire selection. I hear many owners are going with 17 rear wheels to open up tire selection.

Maybe back to the question on race bikes, could it be something to do with spec tires in racing??

[tsorfas]

i would like to know that as well if someone knows details please, not that i would do it but its an interesting topic

[Degsy]

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Smaller wheel, less weight. We used to sell 16.5 tires so I'm sure MTAG can get them. The desmoceidici guys are changing to 17s because pirelli don't or used to not sell slicks to non racers.

[Woodcraft]

The 16.5 inch rims allow for the same size tire (from a circumference standpoint) that has a taller sidewall. The OD's of the tires are what they are because people are the size that they are and the evolution of technology brought us to those sizes. The 16.5 tires that I used were actually heavier than the 17's.

The taller sidewall has the ability to flex more when leaned over, and these tires tended to offer a little better grip. The big advantage that I saw was that the extra give in the sidewall did a lot for bump absorption when leaned over. I went back and forth a few times on the same weekend from 16.5's to 17's, and the 16.5's would make some of the bumps disappear.

I'm sure that the current MotoGP tires are a few steps of evolution past the tires that I used for AMA Superbike....but I would suspect some of the same thought process prevails there.

[Kitt]

The 16.5 inch rims allow for the same size tire (from a circumference standpoint) that has a taller sidewall. The OD's of the tires are what they are because people are the size that they are and the evolution of technology brought us to those sizes. The 16.5 tires that I used were actually heavier than the 17's.

The taller sidewall has the ability to flex more when leaned over, and these tires tended to offer a little better grip. The big advantage that I saw was that the extra give in the sidewall did a lot for bump absorption when leaned over. I went back and forth a few times on the same weekend from 16.5's to 17's, and the 16.5's would make some of the bumps disappear.

I'm sure that the current MotoGP tires are a few steps of evolution past the tires that I used for AMA Superbike....but I would suspect some of the same thought process prevails there.

Nice... thanks! Was going to look it up, as inertia on an extra .250" moment is negligible. I can buy into this explanation.

[Degsy]

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The 16.5 inch rims allow for the same size tire (from a circumference standpoint) that has a taller sidewall. The OD's of the tires are what they are because people are the size that they are and the evolution of technology brought us to those sizes. The 16.5 tires that I used were actually heavier than the 17's.

The taller sidewall has the ability to flex more when leaned over, and these tires tended to offer a little better grip. The big advantage that I saw was that the extra give in the sidewall did a lot for bump absorption when leaned over. I went back and forth a few times on the same weekend from 16.5's to 17's, and the 16.5's would make some of the bumps disappear.

I'm sure that the current MotoGP tires are a few steps of evolution past the tires that I used for AMA Superbike....but I would suspect some of the same thought process prevails there.

Nice... thanks! Was going to look it up, as inertia on an extra .250" moment is negligible. I can buy into this explanation.

Yeah. Thanks Eric. Makes sense.

[backinthesaddle]

So its kind of like the opposite of how MX bikes have gone from 18" rear tires to 19" (with the same circumference) since the MX goal was to reduce sidewall flex and have the bike track straighter.

[Rada]

Eric,
Thanks for the insight. It makes some sense that the more sidewall would help with small bumps at lean.

[Woodcraft]

So its kind of like the opposite of how MX bikes have gone from 18" rear tires to 19" (with the same circumference) since the MX goal was to reduce sidewall flex and have the bike track straighter.

I heard this was to help avoid flats when trail riding...which is why off road bikes still tend to use 18's and MX bikes tend to use 19's.

Although I've been riding them all my life, dirt bike tire technology is not my forte....but this is what I have been told the reason for the 18 is.

[Rada]

IIRC the move to 19" on Dirty wheels was to reduce unsprung weight. This change happened back around 1989. I honestly figured that it was only a passing fad. But here we are still using 19s. The biggest difference that I noticed was more flats and tougher tire changes. Although I do believe that the shorter sidewall did tend to bounce less on choppy terrain.

[backinthesaddle]

Yeah the move was to 19" for mx, so many who ride mx bikes off road have resorted to 18" rear wheels to avoid pinch flats. A couple fads were late 70s/early 80s? honda 23" fronts and 17" rears on a couple bikes. Maybe some experimental 20" fronts as well.

sorry for any thread hijack!

[scottieducati]

In a related note... Pirelli is ceasing the 16.5" tire, and WSBK rules are going to 17" tires... from 2012 or 2013 on.

[Mr. Kurtz]

Yeah, while we haven't heard anything official regarding the 16.5 going away, it stands to reason that when SBK goes to 17", the 16.5 Superbike slick will fade away.

I believe the new KTM 450 SMR will be coming with a 16.5 front wheel, though, so there may be some demand for at least fronts to stick around. Time will tell. For now, they are stil available.