Bias Ply Tire Pressure

[FED 387]

I would go to the extreme and put about 20-22 pounds in maybe even 23-24 --see what happens if it likes it try more---if it doesn't back it down from 20 to 18 see what happens---1/2 or 1/4 pound increments are for fine tuning when you eventually find the sweet spot--you will wear the car and tires out if go the" itty bitty" pound route--are you looking for 60 foot times or are you looking for overall ET & MPH?---you can make a car 60 foot and decrease the overall performance--overall the higher pressure side walls look a bit better but how does the foot print look?? is it wallowing the tires as it moves forward or is the pattern pretty uniform across the tire marks on the track???--FED 387

[Andy Friar]

Originally Posted by FED 387

I would go to the extreme and put about 20-22 pounds in maybe even 23-24 --see what happens if it likes it try more---if it doesn't back it down from 20 to 18 see what happens---1/2 or 1/4 pound increments are for fine tuning when you eventually find the sweet spot--you will wear the car and tires out if go the" itty bitty" pound route--are you looking for 60 foot times or are you looking for overall ET & MPH?---you can make a car 60 foot and decrease the overall performance--overall the higher pressure side walls look a bit better but how does the foot print look?? is it wallowing the tires as it moves forward or is the pattern pretty uniform across the tire marks on the track???--FED 387

The 2 lbs increase and previous reduction in launch rpm are helping the car to plant the width of the contact patch and not pile the tire up on the contact patch. We are going after a solid flat patch, to minimize wallowing and thus decrease launch variances. It is a bracket car that we are looking to refine the combo on for repeatability sake. We are ultimately looking to print timeslips with W's on them

[FED 387]

Andy-- I fully understand the concept of bracket racing --REPEATIBILITY---if the car runs the same number regardless if it has 10 PSI or 20 PSI in the tires who cares what the tires look like at launch--all you are trying to do & accomplish as I understand it is go from point A to point B in XXX seconds correct??? so wallowing, tire pressure , launch RPM, removing a spark plug wire(LOL) etc should not come into play other than to get the same exact number eveytime what ever it takes correct??
I feel the tire needs more air and thats what I would do --plus are the rims drilled for screws? have you tried running with out them?? your sidewall photos would look different as the wrinkles now coincide with the screw location(IF you r running screws) if not then more air will help take away those wrinkles--By the way great looking car !!!!! Also have you looked at the tires in REALLY SLO MO out to about 20-30 feet to see what they are doing and what the footprint looks like as the car is moving forward??--FED 387

[Mike Rietow]

More than anything no matter the pressure you settle according to any given track condition, you want both fires to look identical, it tells you equal force is applied to the tires.

Rearend rotation has it lifting the driver front higher with more force being applied to the left rear. You want the tread and sidewall to wear even..

You can accomplish this with a bigger diameter sway or double adjustable dampers front and rear. BMR used to sell a huge bolt in factory location sway bar and may still..

I see the rear shocks are factory location as well, Viking or vari shock QA! probably sell a factory bolt in D/A for a Chevelle. If you do D/A dampers let us know I'll suggest how to adjust them so the rear bumper is level to the track surface, as it leaves the starting line - wears the tread and sidewall evenly..

[FED 387]

car looks like its twisting from left to right as it launches---left slick does not look as if it is planted the same as the right also rear bumper looks higher on the left side vs right side---might just be the angle of the pic but the right sure looks like its dipping---Also left front tire appears to be higher on the launch but again it could be the angle of photographer--FED 387

[FED 387]

looking at the slo mo from the left side you can see that the right slick is definitely wadding up --look at it real close the inside front of the tire

[FED 387]

Yep --look at .14 on the video starts to wad the tire up