Evil8Beezle:
The Sarge:
Evil8Beezle:
Before we all get carried away with how fast we can overspeed, have a think about the centripetal forces at work on your tyres! 
:
Used to run at 70/80 mph back in the eighties. Pretty sure the tyres are better nowadays, don’t get yer knickers in a knot…
I’m not mate, just giving some perspective as I also overspeed when appropriate, generally when heavy looking to carry a bit of extra speed up the other side of a valley/dip. I just do it in moderation and within certain limits as I’m not getting paid extra for going faster, and I’m also aware that in doing it I’m increasing the potential of an awkward conversation whilst dunking a jammie dodger! 
And as you know, you can’t do anything to cover up the records on a digi tacho, where you could back in the days of paper.
Yes tyres are probably better than they used to be, but I also don’t go over them all with a fine tooth comb during my vehicle checks every time, so there is the potential for missing something. Plus some firms use remolds, and the cheaper the better. So I’m not that keen on giving it large on some badly laminated rubbish, as at the end of the day my licence, liberty and conscience at stake.
Not that it’s really relevant, but I drive highly volatile ADR tankers, so I guess you could say I’m in a mind to think a little cautiously on the topic. But I didn’t go all ‘think of the children’ and ‘killing machine’ in my initial post, that was intended to provoke thought for Newbies, or those that may not have a good grasp of dynamics. So I don’t really think I’m coming across all mumsnet about it, just that it’s worth bearing in mind what’s happening, the forces involved, what that could lead to, and the following consequences for the driver, ASSUMING THEY LIVE! 
(Sorry, had to get that in! 
)
As The Sarge says some of our antics, running at 70mph plus on tubed tyres with no power steering was once common; but I wouldnt recommend telling your life insurance company about it, as theyd increase your premiums. Tyres if looked after are pretty safe, but failure, even if rare, can be catastrophic.
Heat and running under inflated (which increases heat) are more likely to damage and destroy tyres than speed alone. Small wheels run hotter than larger diameter wheels at same speed/load. Brake heat is less easily dispersed from small wheels too. If youre running at any sort of weight or speed, when you stop for coffee, touch the tyres with something sensitive. Not that! Youll get arrested, back of the hand will do. Any tyres under inflated will be noticeably warmer. Tyres do get hot, but over hot tyres can throw a tread and weve all seen the damage done by that. Want some Sunday morning physics? Mixed with a little pedantry? There is NO centrifugal force pulling on your arm: what you feel when twirling a weighted rope around is the reaction to the force you are imparting to said weight to effect its centripetal acceleration. Remembering that velocity is a vector, so even though the speed may be constant, the velocity isn`t. The weight is constantly accelerating towards the centre, so needs the input of a force.
Tyres, especially the walls, are elastic. They are constantly defecting and returning to shape when rolling. It is this that generates heat, due to the internal friction in the side walls of the tyres. Under inflated or over loaded tyres deflect more, so run hotter. More info? Look up “hysteresis”. That will say a bit about heat generation (and energy “losses”) in elastic systems, such as tyres.
NOTE: Due to the increased temp the air pressure inside the tyre will also increase, this is why pressure should always be measured with a cold tyre. Never let air out of tyre when it`s hot, it will then be under pressure when cool again.
OK, we should all know that, but I mentioned it just in case.
