Triumphrat

denny · 11-03-2009, 02:09 AM

I finally found an official answer to an old question of mine.

I understand a tube placed in a tubless tire lowers the speed rating, because of the extra heat that is generated by the tube.

So how much does this lower the speed rating of the tire?
I've looked for an answer to this question for quite some time, so I was thrilled to see this in print on a manufacturer website.

I found this on the Continental website. The portion I highlighted in red is the answer from Continental.

For Continental motorcycle tyres

All TL/TT-sidewalled tyres can be used with a tube without decreasing the speed range (except Z rated radials).
ALL Continental tyres labelled TL can be fitted to rims/wheels marked Tubeless. They can also be fitted on Tubed Type rims/wheels with a correctly sized Continental inner tube.
If Sport Attack, Road Attack and ContiForce tyres (Z rated radials) are fitted on Tubed Type rims/wheels with Continental inner tubes, the maximum speed is then restricted to 130 mph (210 km/h, from Z to H speed rating).
Continental tyres labelled TT can only be fitted on Tubed Type rims/wheels and must be fitted with a correctly sized Continental inner tube.
Please note that the maximum speed for tubeless tyres fitted with an inner-tube is 210 km/h (approx. 130 mph).

I've heard several folks comment about Continental Road Attack tires. So I am investigating those for my TBS.

But they do not make a 160/70-17

Anyone ever try a 150/70-17 on the rear of a TBS?
The OD is closer to a 160/70-17, than a 160/60-17 is.
And 10mm width is really not very much.

Avon and Metzler seem to be the only sites that quote overall dimensions for the various tire sizes. Their dimensions for the sizes mentioned are very close to each other. I can't find dimensions on the Continental site.

faffi · 11-03-2009, 04:38 AM

Going with a 150/70 should make the bike nimbler and increase its stability, and it should also make it less affected by bumps during cornering.

A 160/60 will lower the rear of the bike more, increasing rake and trail, slowing the steering. The profile of the rear tyre is also likely to slow the steering a little. The drop in height will lower CoG, gaining back some of what's lost in agility. Ride is likely to be harsher due to shorter, stiffer sidewalls.

Whether you will notice these differences or not is hard for me to say. It will depend on the actual profile/compound/construction of any given tyre, how hard you ride and what's most important to you. Generally speaking, I would say that the narrower and taller tyre should make the bike a little more pleasant to ride, whereas the lower 60-profile is likely to deliver slightly better mileage from the tyre, but the lower effective gearing will probably nullify any economic gain.

cafetbird · 11-03-2009, 05:48 AM

I've always heard that a good rule of thumb is to lower the speed rating of a tubeless tire by one rating if you install a tube.

Since the TBS suspension is adjustable, you could effectively eliminate most of the negatives that occur from installing a lower or wider tire. Dropping the front end slighty and softening the rear suspension would resolve issues with manueverability and harshness.

One advantage of a larger width tire is increased contact patch, giving you better grip in the corners. Of course, this will be somewhat affected by tire profile. The Conti Road Attack has a "V" shaped profile, so you are going to notice quicker turning with them, and a very well-planted feeling in the turns. They gave me greater confidence in the twisties. Unfortunately, they are shorter lived than the Avon Storms...