Tire pressure on cambered wheels
Discussion
Wow thanks for making me feel like an idiot lol, is amazing what a missing period will do too some specs. The revised numbers are .7 on the front and .2 on the rear. I'm not even sure what a whole 7 degrees would look like. And yes I do have after market suspension and camber plates, but they are set to the minimum allowances. I only increase the rear settings if I'm going out drifting, which is rare as of late.
Cobrafan05 said:
Wow thanks for making me feel like an idiot lol, is amazing what a missing period will do too some specs. The revised numbers are .7 on the front and .2 on the rear. I'm not even sure what a whole 7 degrees would look like. And yes I do have after market suspension and camber plates, but they are set to the minimum allowances. I only increase the rear settings if I'm going out drifting, which is rare as of late.
Hah, in that case welcome!I'd be tempted to wing it - find the standard pressures and vary them by a couple of psi at a time, once it feels right it is.
This is not exactly you average car even for a cobra, the (quick) list of mods are as follows. T56 six speed, flow master H pipes, JLT intake, and the before mentioned suspension. The rebuilt engine only has about 8k on it. Installed lifters, rockers, and timing with ford race parts. 106300 comp cams (stage 3) and livernoise springs. 22cc dished cut pistons, manley H rods, and a forged crank for a 2015 GT. (This is the MMR 4.75L stroker kit) it's been ported polished blueprinted and balanced to 8%. Running 11.5 to 1 compression. Chiped and dynotuned. What are my specs...? Not enough, it's getting a super charger this summer, haven't decided if it's getting a blower or a pro charger yet, any ideas?
Edited by Cobrafan05 on Tuesday 9th February 21:35
Cobrafan05 said:
What would be an upper range of camber before I start to lose cornering performance? I like to go on our weekend mountain runs that are full of switch backs and poorly banked turns, I'm looking for it to dig in a little more. 
Do I read it that you intend some 'enthusiatic' driving on the public highway ?Edited by Cobrafan05 on Wednesday 10th February 00:09
I once got hold of the official formula to calculate tire-pressure for a sertain load , but also the extra's for higher speed for different speedcodes, and for camber angle .
From European ETRTO standards manual 2007 page 14 .
Maximum camber angle of absolute ( so + and-) 4 degrees is adviced there and for low High/Widht division tires even as low as 2 degrees. For higher speed also not higher then 2 degrees.
For 4 degrees it gives small 15% higher needed pressure.
But the formula was also given so I can calculate it for 7 degrees
Formula for the camberfactor Ks is Ks=1/(1.1-0,05x Y )^1,25 in wich Y is asolute camber angle ( absolute -2degr=2 degr)
This filled in with 7 degrees gives 1,4327 so calculated pressure for zero to 2 camber angle has to be highened up with 43,27% .
For between zero and 2 degrees no extra for camber angle has to be added, to the system as ETRTO gives and also american TRA has taken over .
But to my idea for low H/W tires it has to be even more .
At a sertain moment you will get a triangular contact surface on the ground.
Thats probably the reason why the tiremakers-organisations dont advice to go higher then 4 degrees.
mind that the road curve also has the same effect on the shape of the contact surface as a camber angle .
To my opinion camber angle and angle of imaginary axle to the road has to be added together.
Then about the Z speedrating you give.
It does not exist.
I was told by someone of a tire-company that ZR means nowadays that the tiremaker did someting out of the protocol in the tire desigh , and because of that has to give the highening up for speed and lowering of maximum load themselfes. This is used for above 240 km/h/149m/h.
But mostly they also give V,W or Y on the tire and then you can use that system.
Here a picture I made from the system as given by ETRTO for highening up the reference-pressure /maxloadpressure= pressure used to calculate the maximum load up to reference speed of tire.
Also there I am pigheaded and state that best is to use for every speedcode above Q reference speed of 160km/99m/h. Exeptions in the official system is R( 170km/h),W(190km/h)and Y(220km/h).
From European ETRTO standards manual 2007 page 14 .
Maximum camber angle of absolute ( so + and-) 4 degrees is adviced there and for low High/Widht division tires even as low as 2 degrees. For higher speed also not higher then 2 degrees.
For 4 degrees it gives small 15% higher needed pressure.
But the formula was also given so I can calculate it for 7 degrees
Formula for the camberfactor Ks is Ks=1/(1.1-0,05x Y )^1,25 in wich Y is asolute camber angle ( absolute -2degr=2 degr)
This filled in with 7 degrees gives 1,4327 so calculated pressure for zero to 2 camber angle has to be highened up with 43,27% .
For between zero and 2 degrees no extra for camber angle has to be added, to the system as ETRTO gives and also american TRA has taken over .
But to my idea for low H/W tires it has to be even more .
At a sertain moment you will get a triangular contact surface on the ground.
Thats probably the reason why the tiremakers-organisations dont advice to go higher then 4 degrees.
mind that the road curve also has the same effect on the shape of the contact surface as a camber angle .
To my opinion camber angle and angle of imaginary axle to the road has to be added together.
Then about the Z speedrating you give.
It does not exist.
I was told by someone of a tire-company that ZR means nowadays that the tiremaker did someting out of the protocol in the tire desigh , and because of that has to give the highening up for speed and lowering of maximum load themselfes. This is used for above 240 km/h/149m/h.
But mostly they also give V,W or Y on the tire and then you can use that system.
Here a picture I made from the system as given by ETRTO for highening up the reference-pressure /maxloadpressure= pressure used to calculate the maximum load up to reference speed of tire.
Also there I am pigheaded and state that best is to use for every speedcode above Q reference speed of 160km/99m/h. Exeptions in the official system is R( 170km/h),W(190km/h)and Y(220km/h).
Edited by Jadatis on Wednesday 10th February 12:10
OP, you might like to gen up on sports car suspension, understand how it works before making any adjustments or modifications. As mentioned above -1 to -1.5deg for fast road use should be fine but be very wary of going beyond this. For good background understanding buy and digest the following book
http://www.amazon.com/Modify-Sportscar-Kitcar-Susp...
http://www.amazon.com/Modify-Sportscar-Kitcar-Susp...
Cobrafan05 said:
Thanks, I think I'll just put it to 7 at around 60 psi and see if I can't scare the s*it out of myself or some unlucky locals. Lmfao
Where do you live ? So I don't encouter you "scare the s*it out of myself or some unlucky locals"Edited by Cobrafan05 on Wednesday 10th February 13:15
TooMany2cvs said:
He's a Leftpondian. I think the plate on the barge says South Carolina. Which, having been there, would explain quite a lot.
Close, North Carolina, we usually head up to the Blue Ridge parkway in the Boone area. Search Lynn Ridge viaduct. Beautiful scenery, steep drops, no guardrails. It's as back woods as you can get. Good roads once the snow melts. If you don't go home feeling shaky, you haven't had fun.Gassing Station | General Gassing | Top of Page | What's New | My Stuff