Importance of Load Index (tyres)

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Shoppinit
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Importance of Load Index (tyres)

Post by Shoppinit » Tue Jun 11, 2013 12:14 pm

Does anyone know how they are calculted? Or rather how you know which one is appropriate for your car?

Some of the tyres I'm looking at don't exist in the load index for the RS4 (96Y) but they do exist in 93Y.

96 corresponds to 710Kg, 93 to 650, so a 60Kg difference in what the tyre will bear.

But, obviously, both values are waaaay higher than the static weight of an RS4, even fully loaded. So does this mean that this is the max dynamic load that the tyre can take? I can image that under heavy braking you could get close to the load limit.

Or is there just a safety margin built in?

The C6 RS6 is 102! But the C6 isn't that much heavier than the C5 at 96. And the C5 is 200kg heavier than the B7 for the same 96 load index.

But then my M3 is, I think, 91, and that's not much lighter than the RS4.

Confused. :drink:
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
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Re: Importance of Load Index (tyres)

Post by adsgreen » Tue Jun 11, 2013 1:04 pm

It's dynamic weight.
I don't have any data but I'd expect what? at least 70% of the mass on the front axle if you were emergency stop from high speed?
Given that the car is about 1700kgs + occupants (2 adults say 150kgs) + some <beep> in the boot... + 20kgs?
About 654kgs per front tyre...

Personally I wouldn't mess with the load rating.
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Shoppinit
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Re: Importance of Load Index (tyres)

Post by Shoppinit » Tue Jun 11, 2013 1:08 pm

Problem is, all the track day tyres are lower load ratings... :(
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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Re: Importance of Load Index (tyres)

Post by adsgreen » Tue Jun 11, 2013 1:21 pm

Can drop to 18"
Otherwise you've got Pirelli corsa asymetrico or you can get yoko neova's in the right 19" size.
http://www.ears.co.uk/Tyres-Track-Day-T ... _info.html
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Re: Importance of Load Index (tyres)

Post by Shoppinit » Tue Jun 11, 2013 1:37 pm

Can't put 18's on because of the ceramics.

Thanks for the link though. Interestingly that's the tyre I originally wanted, but someone told me it's more of a road tyre, rather than a track day tyre.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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Re: Importance of Load Index (tyres)

Post by adsgreen » Tue Jun 11, 2013 2:55 pm

Pirelli trofeo r's available in 265/35/19 98y rating...
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Re: Importance of Load Index (tyres)

Post by adsgreen » Tue Jun 11, 2013 2:56 pm

Shoppinit wrote:Can't put 18's on because of the ceramics.

Thanks for the link though. Interestingly that's the tyre I originally wanted, but someone told me it's more of a road tyre, rather than a track day tyre.
I'd say fast road light track. Iirc standard fit to Elise but they have to soften the compound for it to work. On a heavier car might work well.
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Re: Importance of Load Index (tyres)

Post by Shoppinit » Tue Jun 11, 2013 3:16 pm

Yeah, a guy at the track in a 458 chopped out his Michelin Cup Sport for some Trofeos and he rates them much more than the Sport Cup. Feck me are they expensive, though.

I find the PSS aren't really up to the job on the track, so I'm really keen to go with something that much more track oriented and only barely road legal. :)
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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Re: Importance of Load Index (tyres)

Post by Mr Footlong » Tue Jun 11, 2013 3:53 pm

Shoppinit wrote:Can't put 18's on because of the ceramics.
Que? When did you get ceramics?
Current:

23' C8 RS6 Vorsprung - 23' RS E-Tron GT Carbon Vorsprung

Gone:

"Brutus"- C5 RS6 Avant - MRC stage 2 - Milltek non-res + 100 cell cats - Wagner ICs - PSS9 - H&R ARBs - OZ Superturismo LM - C6 Custom brakes - HD RNS-E - Various other bits - 555PS/832Nm
"Taz"- C7 RS6 - MRC stage 2 745PS/1095Nm
12' Cayenne Turbo, B7 RS4, S3, Cupra R, XJR, EVO VII, STI8,5,2&WRX, 106 GTI&XSI, other crap.
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Shoppinit
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Re: Importance of Load Index (tyres)

Post by Shoppinit » Tue Jun 11, 2013 3:56 pm

Not my car. :)
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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Mr Footlong
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Re: Importance of Load Index (tyres)

Post by Mr Footlong » Tue Jun 11, 2013 3:57 pm

I did wonder, I even just went stalking your threads as all that RS4 mumbojumbo was throwing me.
Current:

23' C8 RS6 Vorsprung - 23' RS E-Tron GT Carbon Vorsprung

Gone:

"Brutus"- C5 RS6 Avant - MRC stage 2 - Milltek non-res + 100 cell cats - Wagner ICs - PSS9 - H&R ARBs - OZ Superturismo LM - C6 Custom brakes - HD RNS-E - Various other bits - 555PS/832Nm
"Taz"- C7 RS6 - MRC stage 2 745PS/1095Nm
12' Cayenne Turbo, B7 RS4, S3, Cupra R, XJR, EVO VII, STI8,5,2&WRX, 106 GTI&XSI, other crap.
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Re: Importance of Load Index (tyres)

Post by adsgreen » Tue Jun 11, 2013 5:20 pm

Shoppinit wrote:Yeah, a guy at the track in a 458 chopped out his Michelin Cup Sport for some Trofeos and he rates them much more than the Sport Cup. Feck me are they expensive, though.

I find the PSS aren't really up to the job on the track, so I'm really keen to go with something that much more track oriented and only barely road legal. :)
By all accounts a great tyre. They last a few days too.
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Re: Importance of Load Index (tyres)

Post by gdavison » Wed Jun 12, 2013 6:55 am

I find this a really useful read re all the tyre numbers

http://www.btmauk.com/data/files/Replac ... ations.pdf

some of their other files are interesting reading

http://www.btmauk.com/page/useful-infor ... tatements/
Ex RS6 C6 Driver, gone but not forgotten.. The best car I have ever owned
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Shoppinit
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Re: Importance of Load Index (tyres)

Post by Shoppinit » Wed Jun 12, 2013 7:42 am

Interesting stuff. I liked the nitrogen article.

As for the load index, I'm still not sure what to do. The R888 are what I want, but they are 93Y instead of 96Y... Arghhh. What are the risks, if any? Bearing in mind there must be a fairly huge safety margin if the RS6 is also running 96Y.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Top
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Re: Importance of Load Index (tyres)

Post by adsgreen » Wed Jun 12, 2013 2:07 pm

Shoppinit wrote:Interesting stuff. I liked the nitrogen article.
I've said the same things before on nitrogen. Pointless for a road car.
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