ran a 5.1 on stock ps2 than tryd re11 s car ran 5.3 do to 19lbs of rotating weight than pilot sport cups 5.0 all at same boost level and road

 

Weight is a big issue case in point

 

I agree that rotating mass is huge, but you might also consider atmospheric conditions at the time of both runs (temp, baro, and humidity).

 

the re11 to the cups were swapd same day

 

Ok, so I assume runs were also done same day minimizing affect of atmospheric variables.
My understanding is that rotating mass can have 3-5X the affect of non-rotating mass on performance. Thus switching the tires could have been like adding 57-95 lbs to the car...

 

Interesting find ED!!

Do u still ran stock rims??

 

no forgelines

 

Aha...Here is tires weight for the 997 turbo ( thanks to Cannga )

Originally Posted by cannga
While it's not the end of the world to use other tires (and I don't mean to be critical of those who do so), I would stay with Porsche specific, N rated Michelin Pilot Sport N1 (what I would recommend for you to try), or Pirelli PZero. Or... if you want to be adventurous and are not driving the car in the rain or snow, move to the r compound tires, either Pirelli Corsa or Michelin Cup. (There is a thread on this somewhere, but the N rating has to do with tire construction made for the specific rear engine rear heavy configuration of the 911. Anyone corrects me as needed.)

On the tirerack site below, check out the weights of the tires, (as Chris/E55AMG mentioned) some of the tires like the RE-11 are REALLY heavy, and tire being the outer border, it's the worst place that you want to gain weight.

This topic has been discussed many times before, but to make the long story short, moment of inertia is worse the further out you are in the wheel. Heaviness at the rim periphery will affect braking, acceleration, and steering much worse than if the weight is towards center. Whether a driver could feel it or not could be debated, but the effect is there.

Michelin Cup: front 20 rear 27
Pirelli Corsa: front 21 rear 26
Bridgestone Potenza RE-11: front 27 rear 32 (A near 30% weight gain in front!!)
http://www.tirerack.com/tires/TireSe...=58154&tab=All

 

spray some rubberized undercoating on the rims and make a hail mary run without tires... 4.2 60-130 = ) ... just kidding eddie this is an awesome work in progress and im looking forward to you busting into the 4s !!

 

lmao i hope to do it sat or sunday ill keep u posted why dont u come out sun morn 4 breakfast if i go 4s u buy if i dont i will

 

lol sunday sounds good i dunno about that wager though sounds like you are setting me up to lose on that one.. i tell you what.. deal if you give me an over under # but not 5.0 or 4.9 and id like to see you do it with my 240lbs in the passenger seat

 

Well i must be the 1st to say WAY TO GO ED....You can tell them what you ran but i wanted to be the 1st to congradulate you in public...You beat me and your dammm lucky its to cold for me to hook now...Congrates though to you and your tuner....

He is in the 4s now guys...without cheating to..which amazes me

 

lmao i only cheat when i race u you have 4 extra spark plugs