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From: Radey Shouman <shouman@comcast.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Speed, load & temp limits for bike tires
Date: Sat, 22 Mar 2025 01:18:45 +0000
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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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