Re: Speed, load & temp limits for bike tires

Frank Krygowski <frkrygow@sbcglobal.net> writes:

On 3/19/2025 1:31 PM, Radey Shouman wrote:

Frank Krygowski <frkrygow@sbcglobal.net> writes:
 

On 3/15/2025 2:50 PM, bp@www.zefox.net wrote:

Is anybody aware of testing results for the speed, load and
temperature limits of bicycle tires? Something like the DOT
specs for load range and speed rating for auto tires, but
applied to bicycle tires? It's obviously not relevant to
bikes apart from tandems engaged in downhill racing. Perhaps
not even that.
This is an admittedly obscure question, but maybe there's an
answer lurking somwehere I've not found. Probably manufactureres
do it as part of design and production quality control, but whether
results leak into the public sphere is unclear. I ask because I have
a very nice bike cargo trailer (cycletote) which I've pondered
attaching to a small motorcycle. It isn't something I'd do
under normal circumstances, of course. Merely wondering what
might be possible in a pinch.

>
I'm not aware of any such data. I very much doubt temperature is a
significant variable. In the past, this group has had extensive
discussions of maximum temperatures of rims and how they affect tire
integrity, but all that was in relation to rim brakes heating on
super-long descents. A trailer would see none of that.

At highway speeds a standing wave occurs right after the tire
contact
patch.  In the frame of the tire, of course, it travels at the ground
speed of the vehicle.  Repeated deformation of the tire carcass results
in heating the tire and can result in failure, which is why car tires
have a speed rating.  Bicycle tires are not so rated.

>
Since tire rolling resistance measurements by rotating drums are
measuring mostly the hysteresis losses within the tire, we can
probably do some approximation calculations of the heat input. But
decent estimates of heat loss would be much harder, given the
complexity of forced convection. And you'd need both input and output
to get a handle on temperature rise.
>
I'm not going to bother with numerical estimates, because I'm pretty
sure it's a non-issue.

Any accident on the highway with a tire not rated for motor vehicle use
is not going to be a "non-issue", it's going to be expensive and painful.

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