T5 Tyres 17" what is available in OZ

[IN2VWS]

Pinched from the net. Not sure if it is what you are after.

In general, speed ratings of V or above mean that the tire has extra cap plies or even multiple steel belts to provide extra stability at very high speeds.

To answer your questions you need to know a bit about speed ratings and what they really mean, so here's the 10-cent course. The term speed rating is a misnomer; it is really more of a test of a tire's stability over time while driving at highway speeds.

All tires generate heat when rolling. Imagine the sidewall flexing as it goes from fully extended at the 12 o'clock position to fully compressed at the 6 o'clock position. At 100 km/h, the tire of a small sedan rotates about 800 times per minute, generating a lot of heat. So as speeds go up, the heat goes up, until eventually the sidewall gives up and goes bang.

There is a measurement standard for the length of time a tire can run at a given speed before failure. This is determined on a test machine in a lab that simulates load on the tire and cornering forces, etc. The tire must run two hours at a sustained speed to get a speed rating.

A T-rated tire can run at sustained speeds of 190 km/h and be safe. An H-rated tire can run at 210 km/h. Since you don't go that fast, why does it matter? Remember that sidewall flex? Flex can be increased when the tire is under-inflated, when the car is more heavily loaded, and when the car goes around a corner. So a heavily loaded car with under-inflated tires going down a twisty road can really punish a tire.

The only thing that can help the tire is to make it stiffer and better able to dissipate heat. The result is a higher speed rating.

The automaker works out the worst-case scenario and chooses a tire with a speed rating that gives even the least-informed driver a safety net.

[greymad]

"The automaker works out the worst-case scenario and chooses a tire with a speed rating that gives even the least-informed driver a safety net. "
Dummies rule, and the rest of us pay the price, eh?
I put the same question to a tyre dealer today and his version was that the guage of the fibres (he used the word "denier" - I associate that as a term used to describe Nylon stockings...not mine) was different. So if I always have the tyre pressures up to spec. and I never travel over 110k/hr one would think it possible to go down the speed rated scale. But of course we always have the Big Brother Brigade to spoil life for us, don't we.

[Diesel_vert]

The authorities in most jurisdictions will generally advise you to adhere to the original specifications as defined by the manufacturer. In most instances, deferring to the manufacturer on what should and shouldn't be done is usually the most safest and reliable option.

However, the regulations in South Australia requires that whatever tyre is fitted to a passenger vehicle must have a rated operational speed of at least 180 km/h (a speed index of S).

As far as the law is concerned, fitting 235/55 R17 103V XL (240 km/h) tyres on your particular Transporter is more than acceptable.

[greymad]

The authorities in most jurisdictions will generally advise you to adhere to the original specifications as defined by the manufacturer. In most instances, deferring to the manufacturer on what should and shouldn't be done is usually the most safest and reliable option.

However, the regulations in South Australia requires that whatever tyre is fitted to a passenger vehicle must have a rated operational speed of at least 180 km/h (a speed index of S).

As far as the law is concerned, fitting 235/55 R17 103V XL (240 km/h) tyres on your particular Transporter is more than acceptable.

Thanks... I spoke with (another) tyre guy today and he is reading from the same page as you re speed ratings: different when talking about load ratings, however - and I'm reasonably comfortable with that, although the "safety margin" applied seems to be super generous/conservative in most cases.

[A team]

Has anyone had Kumho KU27's.
Apparently they are long lasting but what are they like for noise, grip, etc.
What else is out there for around that $200 mark thats good value?
Any help would be appreciated.

[Sunny43.5]

So South Australia regulate the rating to 180kmh question what is the speed limit in SA ??? I just checked maximum on some roads 110 kmh don't make much sense does it .

[Transporter]

So South Australia regulate the rating to 180kmh question what is the speed limit in SA ??? I just checked maximum on some roads 110 kmh don't make much sense does it .

The tyre rating has to match the max. speed of the vehicle.

[Diesel_vert]

A tyre's speed index not only indicates its maximum operating speed (as defined under specific and ideal conditions), but it can also be reflective of its construction.

I think a safe vehicle is a vehicle where every component is able to withstand whatever the vehicle is capable of, irrespective of whether these capabilities are limited by the road rules.

I also think a vehicle should not behave in a manner or be driven in a condition that would present itself as a hazard to other vehicles on the road.

So South Australia regulate the rating to 180kmh question what is the speed limit in SA ??? I just checked maximum on some roads 110 kmh don't make much sense does it .

Vehicle manufacturers, tyre manufacturers and the road authorities highly recommend that replacement tyres have the same load and speed index of the original tyres.

I would also agree with this principle:

The tyre rating has to match the max. speed of the vehicle.

But as it is, most states only require that any tyre fitted to a passenger vehicle be capable of 180 km/h or higher.

[Transporter]

Well, the principle or not, you won't buy a new car capable of the max. speed of 200km/h or higher, with the tyres that are rated to 180km/h only.

Also, the speed rating may be less when the tyre that is rated at 180km/h is 5years old, only 1.5mm of the tread ramaining and was punctured and repared. I also beleive that the tyre that was repaired has not the same guaranteed speed rating.

However the law may be different, my reply to Sunny43.5 was to his responce to 180km/h when the speed limit in the state is only 110km/h and to remind him the above.

If, and only If, I'd need to rush my family member to hospital and the road conditions allow, I wouldn't even think about the speed limit on the road or getting the ticket or losing my licence. Would you?

So, the tyre should always much the max. speed the vehicle is capable of.

(for the smart ones, we have the ambulance cover, that's why I used "if" ).

[Diesel_vert]

However the law may be different

It is.

Every state in Australia only requires that any tyre fitted to a passenger vehicle be capable of 180 km/h or higher.

So, the tyre should always match the max. speed the vehicle is capable of.

I agree with that, but I'm only stating what the law is - I didn't say it was good law.