RS4 SE

You know racing Audis, will a set of Pirelli 235/645 18 slick work on the RS4? I know that most guys buy and recommend 255 or 265/18 for a heavy car but I had Toyo888 225/40 18 on my B7 S4 and they work ok for me.

I will get a set of new Pirelli slicks for a great deal and thinking of putting them on my OEM winter wheels (7,5x18 ET20)

What do you think?

bhvrdr

you will be doing in a 235 will perform better then even a sticky street tire like a PS2 or bridgestone 01r in a 265 size.

RS4 SE

Full racing slicks Pirelli D3

S4iowa

larger

ttstore

245/40/18 Nitto NT 01R's work great on OEM RS6 take offs, that's what I use

bhvrdr

to the rim and a 235 on a 7.5" wide rim is within limits.

bhvrdr

wider road tire. Even my crappy RA1 tires would smoke the **** out of a grippy street tire.

RS4 SE

Thanks for your input Mike!

Bob W.

especially if the load rating is inappropriate for the RS4.

Jet Jockey/A4 Pilot

I actually called Pirelli USA today for you to get that info but no one at the race division was available but I left them a message and perhaps they will call me back.

First, I'm not sure if they would actually recommend a 7.5" wheel width with this tire. The minimum width "suggested" wheel is 8 inch according to the web site but anything goes when it comes to racing.

Second, I'm also curious about the weight/load factor for this tire. The RS4 is ~ 4000 lbs and a 235/40/18 series tire could be too low but again in racing, everything goes.

If I or you can find out about these two factors then you would be all set.

For those who want to know about this tire here's some info...

It's the Pirelli P Zero full race slick. The D3 designation is the hardest compound available in this tire, the D6 is the softest. Depending on tire size some compound are not available. The 235/645/18 only comes in D3 compound.

BTW the "D" stands for "Dry". They also make "W" types like a W3 or W6 which of course is you guessed it "Wet".

Another thing that most people don't know and may be confused by is the "645" number on this tire. It seems some race tires use this method of measurements for the sidewall height. It is a metric number that means 645mm in diameter.

The 645 in this case represents ~ a 40 series tire. Here's the breakdown of the numbers associated with this tire a 235/645/18...

235mm = 9.65" (section width).

645mm = 25.39" (overall diameter).

18" is self explanatory.

This tire as a 225mm = 8.86" tread width.

So how do I get a 40 series tire out of 645mm? First I have to assume everyone here knows that the series or sidewall height is a percentage of the tire's overall diameter and its section width. Because there are both metric and English measures in a tire we have to juggle the numbers a bit. So here's the answer...

We already know it's 25.39" (645mm) in overall diameter and that it's an 18" wheel.

So 25.93 - 18.0 = 7.39". Take the 7.39" and divide it by 2 and you get 3.695".

This 3.695 inches is then multiplied by the factor of 25.4 Inches to mm) and gives you this final number; 93.85mm.

93.85mm is then divided by the section width of 235mm and you come up with 0.39936 which is the equivalent of 40% or a 40 series tire.

93.85/235=.39936 or 40%

Hope that clears up some of those numbers for those interested.

Another important technical info about the P Zero race slick tires and cold temperatures. Pirelli <b>will not warrant</b> these tires for a condition called <b>"cold cracking"</b> due to tires been <b>used</b> on track and/or <b>stored</b> at temperatures below 40F or ~ 5C. This even includes the <b>shipping</b> process, no shipping at low temperatures.

BTW I don't consider myself and expert just an enthusiast and I certainly am not a racer or a pro at this hobby. However I do compete in some timed track events and do some HPDEs and some lapping.

Thanks for the compliment anyway.

Mike