Tire PSI - Page 2


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Thread: Tire PSI

  1. #11
    Senior Member kiryu's Avatar
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    Re: Tire PSI

    Used to do 45/41 like the sticker says. I never understand why the car understeer so badly in canyon driving. A friend said factory went 45/41 for the mpg (who knows?), and recommended 36/37. I have been doing 36/37 since. The car still understeers, although not as bad as before. However I think there's little difference if you just do freeway and regular street driving, maybe a bit stiffer over bumps with 45/41.
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  3. #12

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    Re: Tire PSI

    I recommend running what the door says. I run and would recommend 45/41 psi as the door says for my Gen1 V10 (USA) on PS4S's. Agree with everyone on these Michelin's and just gave detailed response in a Pzero thread. A lot of running and effort was put in at Audi at the recommended pressures for your car unless you are pushing it enough for noticeable build in pressures (and not high speed - over 150 mph). If you build 4 psi then you can drop them that much. But should be the same drop front and rear. We actually had two pressures on the door of the '05 Ford GT 32 psi front/32 psi rear up to 150 mph and 40 psi fron/40 psi rear above 150. Tire testing and regulations changed a lot in the US causing us to do two pressures. Keep in mind the FGT has huge tire sidewalls compared to the R8 and we did all of the design and development at 32/32. But Audi appears to have done the split and much higher pressures.

    Tire pressures - the car lists high pressures for the low profile tires (durability) and high speed running. I am pretty certain not for fuel economy on the R8.

    Lower pressures are better for rough road grip, but worse for what we call cornering stiffness. So the steering will not be as good and the car will not be as direct or have as much capability up to the limit with lower pressures. At the limit of pure handling it is harder to say, but not a given that one way is better other than test it back to back. Both ways.
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  4. #13
    Senior Member Wcclubchamp's Avatar
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    Thanks Scott. Good info for sure. When they came out from the 35k service they were set to 44/41 f/r. I had them set to 39/36 which was what they were when the pre purchase inspection was completed. I am more of an in and around town driver or smooth joy ride, although the track would be fun! I would love to take it out, just picked it up 3 weeks ago, but certainly am far from a “pro” when it comes to driving. I live in Rocklin, CA and there is a Sonoma raceway up in Napa which I would love to take it to!

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  6. #14
    Senior Member ezmaass's Avatar
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    Re: Tire PSI

    So, does anyone know why Audi apparently switched from higher to lower pressures? My 2015 calls for 39/36 like many of the others here. But it sounds like earlier cars called for 45/41?

    I've kept to the 39/36 called out on the sticker.
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  7. #15
    Senior Member GT#298's Avatar
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    Re: Tire PSI

    I thought 45/41 was just a GT spec.
    Now I'm curious what defines those specs.

  8. #16
    Senior Member ezmaass's Avatar
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    Re: Tire PSI

    Quote Originally Posted by GT#298 View Post
    I thought 45/41 was just a GT spec.
    Now I'm curious what defines those specs.
    That's what I was initially thinking when I read your post, but it looks like Kiryu and Scott are both saying their stickers (standard V10) show 45/41, but others (including myself), have 39/36 stickers.
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  9. #17
    Senior Member three_dead_trolls's Avatar
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    Re: Tire PSI

    interesting. my 2011 manual Gen 1 lists 45/41 on the sticker as well. Its not a GT

    Wonder what differentiates the 45/41 recommended spec from the 39/36 spec?!
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  10. #18
    Senior Member WinterRunner's Avatar
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    Re: Tire PSI

    My sticker says 45/41, it's a 2012 V10 base. I run 40F on 235's and 37R on 305's PS4S. It's a good compromise with the ****ty roads we have in Mass.
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  11. #19

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    Re: Tire PSI

    Quote Originally Posted by Wcclubchamp View Post
    Thanks Scott. Good info for sure. When they came out from the 35k service they were set to 44/41 f/r. I had them set to 39/36 which was what they were when the pre purchase inspection was completed. I am more of an in and around town driver or smooth joy ride, although the track would be fun! I would love to take it out, just picked it up 3 weeks ago, but certainly am far from a “pro” when it comes to driving. I live in Rocklin, CA and there is a Sonoma raceway up in Napa which I would love to take it to!
    Glad to help Wcclubchamp. I would go with the door sticker as all of Audi's normal development should have been at or around that pressure (especially the split front to rear) and that is what they finalized. The door sticker is mandated by NHTSA to have the correct pressure. BTW I believe Audi chose the split with higher pressure front for smaller sidewall and steering precision and better rough road grip rear.

    I know a lot want a neutral car but even my world class drivers like Bobby Rahal, Kenny Brack, Max Papis, Carl Edwards, Matt Kenseth, etc benefitted in lap time from a car that was just to the understeer side for multiple reasons. And some benefitted from more understeer than others, especially with such huge HP. On the road, healthy understeer is imperative. Especially if you have to do an evasive maneuver that is aggressive like a double lane change. Or when I just had to drop throttle in the middle of a beautiful 90 mph sweeper (for a car that was about to come out from a side road mid corner...out on a country road) and the R8 nose tucked in a little with minor correction, but nothing major. Had a I been in an older 911 it would have been a serious driving event.

    Driving well just takes seat time and a good coach...at the track in a far safer environment than the road. You have an incredibly capable car in the R8. I am extremely impressed. I am not sure if they are still doing driving schools at Sonoma, but if they do I would go. Sonoma is a cool track. Last I knew they didn't have a lot of track days and their noise restrictions were really tight...aftermarket exhausts on just about anything, especially the R8, would not pass. The biggest driving tip I can give as far as driving faster is looking ahead. Far ahead. Sounds quite easy, right? It is not. Most people start out looking down close to the front of the car. The faster you go the more you have to look ahead. 60 mph corner you should spot your entry point 100 feet plus out and start looking for your apex (mid corner) and use your peripheral vision to know where you currently are on the road/track. Then spotting exit and so on. Looking ahead lets you carve one smooth arc and not constantly course correct. It also slows everything down and you get a better sense of yaw. Just like any speed sport you go where you are looking. Blasting through the trees on a snowboard you focus on the gaps...focus on the tree and you will hit it! Focus on something off road/track (especially if you are sliding or heading that way) and you will surely head that way.

    You also have one of my top two road course in the country out there, but again their noise restrictions are tough. And that is Laguna Seca. So incredible the way it flows with elevation and blasting up to the world famous Corkscrew. Very difficult to get right. Enjoy your great car and incredible roads out there!
    2012 Audi R8 | V10 | Manual | AWE Exhaust | Carbon Blades | Carbon Engine Bay | Tuscan Brown Interior 2009 Buell 1125R | Barker Exhaust and ECM Tune | Michelin Pilot Road3's

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  12. #20

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    Re: Tire PSI

    Quote Originally Posted by ezmaass View Post
    That's what I was initially thinking when I read your post, but it looks like Kiryu and Scott are both saying their stickers (standard V10) show 45/41, but others (including myself), have 39/36 stickers.
    I just verified with the Audi dealership (and was fairly certain) that mine is a standard V10 - not a plus. Engine code BUJ. My sticker and owner's manual say 45/41. The sticker is mandated to be "right" by NHTSA. I am not sure on the owners manual and don't understand the contradictions you guys are noting...especially if the manual came with the car. Its not that I don't believe the contraction you guys are seeing it is just that the tire pressures are a big deal and seems like a big "miss". The door jamb numbers should supercede all.

    The event that is hardest on the tire and builds the most heat is speed. By far. 150 mph plus for any length of time and you are building serious heat in the tire. Depending on the oval our infrared tire temps go down in the corners...

    So my judgment is that Audi found over time for the more "normal" R8's and usage that they could get away with lower pressures and bias toward ride in more recent years. And left the pressures at the high for the Plus and GT models as they were more likely to see high speed. Not fact, but my best judgment.

    I will run the lower pressures this weekend to get a feel for the difference now that I have the PS4S's on the car.
    2012 Audi R8 | V10 | Manual | AWE Exhaust | Carbon Blades | Carbon Engine Bay | Tuscan Brown Interior 2009 Buell 1125R | Barker Exhaust and ECM Tune | Michelin Pilot Road3's

    Ahlman Performance LLC | Audi R8 Ohlins Coil-Overs | Chassis Development

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