Where do you get that the load & speed ratings are only a "recommendation" and not a "requirement"?
Because I am using the term 'requirement' in it's legal (lawful) sense.
The law requires only that the tyres are suitable for the purpose they are being put to. The MOT tester doesn't check the load rating or speed rating (officially)
The manual carries with it no imperative for the driver to fit only the tyre sizes, of a particular speed rating or loading that it mentions. Those appear to be mere suggestions of suitable tyres.
if the sizes in the manual were calcualted using a scientific method then an explanation should be sought for why a 1.8 jts has either 215/55 R16 93V OR 225/50 R17 98W for the same car. The speed rating increased by one increment, but the load rating increases by 5 ?
Similarly, the 215/55 R16 93V is recommended for the 1.8jts AND the 1.9JTDm (for versions/markets where applicable) and yet the 1.9 JTDm is 100kg heavier and has a 50kg greater front axle load capacity. Not to mention that the 1.9JTDm usually has 225 or 235 width tyres
Take another two examples from the manual again -
1.8/1.9jts with optional 18" alloy options have a spec of 235/45 98W .
The 2.4JTDm 200hp car also has the same spec tyres
but yet, a 2.4 JTDm has a gross weight of 2135kg and the 1.8 has a gross weight of 1935kg, the 2.4JTDm has a top speed of 231kmh and the 1.8 has a top speed of just 208kmh
With such significant differences in speeds and load ratings on the same spec tyre, can the contents of the manual be taken to be anything but recommendation?
If load rating is the important factor, then why have such large discrepencies in 'recommended' tyres ? General specs like these cannot be mistakes and they shouldn't be interpretted as being 'requirement'. The law is the only thing which can 'require' a certain tyre. The manual merely 'recommends' one.
Has anybody you know had an insurance claim declined based on the fact that a tyre's load rating was different to that in the manual ? I never have. I have seen them turn people down because they had wildly different wheel and tyre sizes to those considered to be 'standard', but never for load or speed rating differences, and only once it was established that the wrong size tyre impeded braking significantly or affected the handling of the car prior to the accident.
I guess we need to just phone an insurance company to find out what they say though...As far as I know there isn't a court which would support an insurance company for being so petty as to refuse insurance based on a person not fitting a recommended speed or load rated tyre.
In the UK, the tyres fitted must be rated for 70mph and I don't think you can even buy tyres which aren't rated for 70mph. If you have an accident while travelling at 80mph, your insurance company is most likely going to void any claim because of the excessive speed, not because the tyres weren't to the manufacturers recommendation, so fitting a speed rating of higher than 70mph isn't going to win you more favour with an insurance company.
Again though, if anyone has had insurance declined because the load or speed rating of their tyres was even a few increments from those written in a booklet which is assumed to be existent in your possession (I've had cars with no manual) is ideal material for 'no win no fee' lawyers.
I think if you were questioned by your insurance company, then a suitable defence (not that you even needed one) is
"In the absence of any information I took the prudent step and can exhibit due diligence by showing that I consulted with the law on this matter"