fao lsp and other police persons.

[lambert]

what does the law say with regard to fitting narrower tyres than manufacturer spec?

[Bush Tucker Man]

what does the law say with regard to fitting narrower tyres than manufacturer spec?

At a guess, the important things are speed & load ratings


Just so long as you're not going 'silly-narrow', but replacing a '235' (or '265') with a '205' will be fine, as that's the original size (presuming it's the Discovery that you're on about)


'Space-saver spares' are for temporary use only

[Hightower]

Don't forget that your insurers may want to know as well . . . . . . .

[lambert]

sorted now. apparently it depends on speed and load rating tho if a tyre is m+s marked speed is exempt. insurance are not bothered.

[Lord Shagg-Pyle]

As far as I'm aware, the only rule is not to mix cross ply with radial. Or am I just showing my age?

[hairyasswelder]

As far as I'm aware, the only rule is not to mix cross ply with radial. Or am I just showing my age?

At 146 years old you must remember solid tyres  :lol: :lol: :lol:

I'm only a spritely 135  :dance: :dance: :dance:

[Range Rover Blues]

if a tyre is m+s marked speed is exempt

Who told you that :-.

[lambert]

northeast tyre and exhaust, why, are they wrong?

[Discopoo]

If it's marked M&S it will still have speed rating, all tyres have a speed ratings. Genrally the speed rating of an M&S is lower than a standard radial tyre

[McGuire]

 In my day you could go up one size in width, but never down. Have things changed?
 

[lambert]

ok to further muddy the water on this, where is the width of a tyre measured? cos when i layed a 205 on a 6 inch rim on the floor next to one of my 750's on a 5.5 rim the overall difference in width was minimal in favour of the 205 yet the tread on the 750 is a lot narrower, so how does that effect things? ie is it overall width or tread width that is measured?

[clbarclay]

For a start the sidewall dimensions are just nominal figures and IIRC should apply to the carcus of the tyre, not the contact patch. Quite a few manufactures produce size tables for theire tyres which list the nominal size as well as more accurate figures for diameter, width at widest point (on a specified rim width), tread width etc.

[Lord Shagg-Pyle]

Hmmmmmmm. Limpets.

[ChrisW70]

If it's marked M&S does it have the St. Michael mark on it somewhere too? 

[Lord Shagg-Pyle]

Of course. thank the lord that Ann Summers didn't market it!

[Range Rover Blues]

ok to further muddy the water on this, where is the width of a tyre measured?

The nominal width is measured at the point where the tread meets the sidewalls if that makes sense, more or less the widest part of the tyre.

northeast tyre and exhaust, why, are they wrong?

As far as I know the manufacturer has to specify the tyre rating and that becomes part of the type approval.  The new RR has a section in the handbook refering to the fitting of M&S tyres and the maximum speed, infering that they have been tested and approved with them fitted, otherwise I don't think they are legal.

You have to fit a tyre appropriate to the vehicle, for examp,e a TDi will do 98 mph flat out, so you can fit Q rated tyres (99MPH), the 3.5 V8 would do about 104 so you have to fit S rated, rated at 108 if memory serves correctly :-k

My LSE runs H rated tyres now.

[lambert]

problem solved; turns out that xpc's have 2 speed ratings which are dependant on load i.e. at 1800kg axle load they are 99mph or at 2000kg axle load they are 87mph so as a disco has a max rear axle load of less than 1700kg and the tdi will only do 97 mph max i'm back to normal. yay!