Tyre ratings

[stephen low]

G'day all

A useful question for all you wanna be racers getting ready, but important for me for engineering - is there an ADR requirement for a certain level of tyre rating?

I ask as I'd been alerted to a potential requirement for V rated tyres that my rear set fall well short of, they are only S rated. These came with the car and it is just another factor the previous owners seemed to have overlooked, once again.

Could I get through initial engineering with these tyres?

I do plan on getting good rims and tyres down the track, but this might speed up the process if I am unlucky.

If I am running foul in this area, anyone got spare rear rims and tyre that I could borrow to get through engineering?

Cheers

[LoBelly]

I'd put in a call to the engineer.

When I first discussed the build with Enkleman I was told that for my car I'd need H rated tyre (210 kph).

From memory, the only appropriate one that I could readily find was the Yoky 352. The BFGs are an S rating (180kph).

As with many things its a matter of what the engineer deems appropriate.

Mine Jetzons are a T rating (190kph) and you're welcome to borrow them if they'll do.

LoBelly

[400TT]

yep, S rated tyres are no longer acceptable.

As LoBelly indicated, best to contact your engineer.

I've also got T rated tyres. 15" Yokohama AVID S/T.

[stephen low]

Was doing a bit of reading yesterday and all the articles I read including VicRoads own guidance document to car roadworthiness testing talked about S rated tyres as being ther minimum standard.

This being case doesn't that make them legal or do the ADRs somehow over-ride and lift this standard further?

I am also asking a similar question of my engineer at the moment but though recent experience here might generate a quick answer.

If forced to get new tyres I'd look immediately at replacing the rims too, though this was planned a bit further down the track. Had originally wanted to stay with the old 15" 60 series tyre look but have gotten use to the 50 profile on the front tyres but the 15" rim generates way too much gap above the tyre to the mud guards. However it is my rears that have the suspect rating, the fronts are V rated.

Going say 16" rims is there a large range of rims and 50's tyres in this size to choose from? I want to run Halibrand look and would be happy with middle of the range dish though I suspect the GF can accomodate quite a deep dish variant.

Any discussion would be great.

Cheers

[400TT]

They certainly do.

I assume it also mentioned that the tyres had to meet or exceed what is detailed on the tyre placard as well.

So Vic Roads accepts as a minimum S rated tyres for all the old clunkers. You know the ones that would have had cross-ply's from the factory.

Vehicles that comply with the current ADR's need to have minimum of H rated tyres. You should check this with your engineer on the specifics of this.

For example, you can't go and fit S rated tyres to a brand new Commodore. You must fit tyres that are equivalent to what is listed on the tyre placard and these will be ADR compliant tyres for that vehicle at the time (Not that you would find S rated tyres in a suitable size for a current Commodore anyway.)

It's only really a problem for those of us using 15" tyres.

[David Hodgson]

Slowy,
Do a search on 'V Rated Tyres' by Cameron parsons in june 2004, there may be useful info there. He basicaly had the same delema.

Can't figure out how to attach a link. Something new to learn.

As I said in that thread, my engineer determined the speed rating by a calculation of theoretical top speed derived by an equation of revs at max power/torque (can't recall which) and gear ratio's and tyre circumfrence.

[David Hodgson]

Try this

www.clubcobra.com/forums/showthread.php?t=58614&highlight=speed+rating

[NASSTY]

Hi Slowy,

As I understand it a lot depends on your Cobra's top speed potential which is determined by your Cobra's overall gearing. As you have a T5 which has an overdriven gear then your Cobra has the potential to exceed 210 kph (H rated) and you would need tyres to suit. Also you need matching tyres as well for your car to be roadworthy; same manufacturer and brand.

Cheers

[stephen low]

Thanks guys for the comments. Still awaiting my engineers thoughts on the subject but agree that I'd want to match or better my tyre's capabilities to that of the car's potential. Hate for a blow out down the back straight of some race track, that might end in tears or worse.

Provided pairs of tyres are matched, that is legal so I think the worst case position for me is two new rims with suitable tyres. Will just have to hit the house loan again!!

Cheers

[400TT]

You won't have a problem with them blowing out. The weight capacity that the tyres are S rated for is significantly more than when used on a Cobra. And that's how we used to argue being allowed to fit S rated tyres in the old days.

[Steve R]

test test test

[stephen low]

Craig

Thanks for that angle, it might come in hand in a debate I've yet to have with my engineer I'm guessing.

Steve R what are you so test'y' about?

Cheers

[400TT]

For the brand tyres you have, look up the specs online and find out the exact load ratings(weight). You know your Cobra weight(roughly anyway). Should certainly help sway him.

I've heard that they prefer the higher speed ratings these days, but that just might be all the 16", 17" & 18" tyres being used.

[stephen low]

The good news is that my sensible engineer, knowing more than he wants to concede, is likely to sign off on my S rated tyres.

By my reading these are the minimum standard for our cars in Victoria and he as much agreed with that.

So at least I'll have some more time to wear out the set I have before upgrading wheels and rims - hooray.

The other interesting advice I got was regarding sun visors, as I had been told they were required. Again not required but if fitted have to be ADR compliant.

All too easy at the moment, but reading the other horror thread on noise controls I can only agree we need to collectively generate a set of rules to avoid being crushed by bureaucratic microbes more intent on the bigger car picture.

Have to raise this one at our next club meeting.

[400TT]

Great news.

Once on the road, it shouldn't take you long to burn up your existing rear tyres.