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      02-16-2017, 04:59 PM   #54
Amgeater2
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Drives: F82 M4, i8, 2nd Gen NSX
Join Date: Jul 2013
Location: South. FL

iTrader: (2)

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Originally Posted by SteveB_UK View Post
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Originally Posted by Amgeater2 View Post
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I've had a rethink on keeping the stock tyres after driving on them in cold weather where normal "summer" tyres perform badly i.e. < 7C. I was pleasantly surprised by the amount of grip the stock tyres offered to the point that I will likely keep them as the compound must be a little softer than normal for them to work so well in the cold and wet.

Shame the i8 specific compound isn't available in larger S001 sizes! I want larger tyres as a little extra rim protection from the kerbs - the grip levels are fine for a road car.
Incorrect the S001 is avaliable on a 275 35 20 with the same compound as the stock sizes 280 A A
This is not advertised as an i8 compound. How can you be sure it is the same?

The fuel efficiency and wet grip ratings differ between the 275 and 245 i8 tyre. This means they are not the same compound.
I listed the compound for you on my prior post : but if you want re-assurance here it's

Rear:
245/40R20 99W Load Range: XL UTQG: 280 A A Sidewall Style:
Blackwall Star BMW (original BMW equipment)

How you can see the compound is the same 280 A A
You've listed complete details of the actual i8 tyre but just said that as the treadwear, traction and temperature grades are the same on the 275 then the compounds must be the same.

Here's what is listed on the site I tend to buy tyres from:

http://www.oponeo.co.uk/tyre-details...32420799_label

This shows the compound as F (efficiency) and B (wet grip - braking)

The other 275 available:

http://www.oponeo.co.uk/tyre-details...-ro1#124991763

This shows the compound as E (efficiency) and C (wet grip)

These are clearly two different compounds and potentially sidewall construction as the ratings are different.

Now let's look at the actual i8 tyre:

http://www.oponeo.co.uk/tyre-details...w-i8#132037890

This shows the compound as E (efficiency) and A (wet grip)

Again different compounds. Highlighted by the wet grip capability.

The load ratings of the 275s and the i8 tyres are also different. Potentially highlighting different sidewall characteristics.

The 280 A A that you believe means the tyres are the same is not sufficient to make that assertion. Have a read of:

https://www.tirerack.com/tires/tiret....jsp?techid=48

One of my friends works for Nissan and his job was specifying and testing the compounds, sidewall construction, etc for their cars. There is a lot more to a tyre'a construction than data you're using.
As you wish don't buy them I have over 14 years in the wheel and tire industry so I think I know a little bit a about what compound means and how it's rated.