indeed, I'd rather drive a roadster with fenders than get 15 years jail time for assualting a police officer. Plus the inevitable beatings you'd get "falling down the stairs" in the police station...
Plus I suspect if you had to drive in our weather you'd find that fenders help you see where you are going. I know a lot of people run small, detatchable ones. clip em on if it rains, clip em off if its nice.
"sorry officer I forgot to refit them" would probably be a better line than getting a beating over it.
I just redid my calculations. They are rough but will be accurate enough for our purposes, to get a general order of magnitude of the forces involved.
Area of sidewall is 150,000 square mm for a 195/45/15 tyre. This is 233 Square inches. At 30 PSI, this is 6990Lb total force. Lets assume half of this is pushing the bead outwards. This gives us 3495Lb, or 1587Kg.
I can't really calculate how much it will take to pull the sidewall of a tyre out an inch, but I'm sure we can agree it isn't going to be much more than 200kg, still giving us a nice margin.
All very lovely calculations and I'm not mathmatical enough to argue about them, but I would say if you have a 1000kg car and its pulling 1G on a corner is that not 1000kg trying to move your tyres sideways?
now lets say that force is spread 75% (i think its probably way more than this after seeing a lot of fwd cars picking rear wheels up on hard cornering) onto the outside two tyres thats 750kg through 4 sidewalls which is about 187kgs each, so its not far off your 200kg is it? and it don't take into account any bumps in the road or the fact the your trying to put power down or the fact that I'm pretty much sure the forces are not spread equally between the inner and outer sidewalls on the tyres.
I know what you are saying - but the 1500Kg force was really calculated to show the magnitude of the force involved, compared to the force of the "stretch" pulling the tyre off.
I do agree that stretch will mean you have less room for error, but again only in the same way that having very low profile tyres will.
In my experience, tyres that are too narrow for the rims to which they are fitted interfere with the front/rear brake bias. Many years ago I was a taxi driver and I drove a 1986 2.0d Nissan Bluebird which I thrashed to near-death every day. One weekend my boss replaced all four tyres with new ones which were noticeably narrower, after this I noticed that, under heavy braking, the rears would lock up way before the fronts had reached their limit. I'll never forget the time when a bloke stepped into the road in front of me without looking one wet morning, luckily he saw me and dived out of the way but the look on his face as he watched me slide gracefully past, COMPLETELY SIDEWAYS, on a very busy city street, was priceless.
Haven't read the whole thread but it's nice to see that the comments are generally of a more intelligent nature than can be found in discussion of the same topic on other forums and was impressed with SOME of the attitudes of the men in blue in the link.
I don't know if anyone has touched on this but in Germany you have the TuV testing - for those that don't know it is stringent and the product subjected to the test is pretty well destroyed during the testing. When Paul Quince was running Dubmeister and Marketing the TH mono's I believe he had them sent over so he could legally sell them on the German market. TuV affects pretty much everything from what I can make out (I have had a pkt of clothes pegs with Tuv approval on them!). Similarly some German wheel manufacturers have recommended tyre size usage guidelines and I would imagine that for them to be able to do that the wheel and tyre combo's would have to be tested.
apologies if that reads a bit murky, it was a few years ago that I worked there and my memory is shot. I will see if I can get some clearer facts or links. What I am skirting around is, if there is TuV approval on running certain wheel/tyre combo's then could that itself not stand as an engineers report being as TuV seems to be somewhat more encompassing in evaluating standards than our own BS system. We are in Europe after all, albeit when it suits - and not when it suits.
The thing is, if you are running tuck and not poke do you need stretch?
i havent read the whole thread ...but if the conclusion is that stretch is unsafe ..has anyone seen the spare wheel you get with a porsche cayene? if i can get the pic off my phone i think it will turn the whole thread on its head!!!!!!!!!!!!! if porsche consider it safe then make your own conclusion!!!!!
The prevalence of the 'arrest first, decide on offence later' attitude shouldn't suprise me, but the ignorance shown on the thread on the police forum is unbelievable. 90% of the posters in that thread took the view that 'it looks wrong to me, so it must be illegal', despite having no knowledge of or experience with the relevant legislation.
Essentially the lesson to learn here seems to be-don't take the pi$$ with mods, and hope the fuzz don't notice them. Otherwise there's a good chance you'll be pulled and fined on the basis of some ill-informed berk's opinion. But we already knew that.
I've a lot of mates that have full spec drift cars s13's and s14's nissan 200 sx's and run stretched tyres all the time and my mate has had his 450bhp skyline powered s13 around a bumpy drift track at santa pod and never had a tyre come of the rim and he is running 10j wheels with 225/40x18 tyres on his just shreds the tyres and never had one come off any drift cars that we have done but the grip is noticeable as if he had the right size rear tyres would be much faster on the road but 1 degree negative rear and 5 degree's front camber doesn't help as I said set up to drift but is a serious fast car if he converted from drift spec to track or fast road. I used to have a high spec classic shape mini with 108 bhp and 600kgs and ran 7jx13 with 175/50 tyres on that and they were stretched and had track and road abuse and getting it on 2 wheels around a fast corner didn't pull the tyre off as that was the biggest tyre i could get that would fit the mini but can now get 195/45x13 tyres.