Taller or shorter tires for the track?

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Mopar to ya

Mopar to ya

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I am hitting the track this Sunday. I usually switch to P255/60R15 Mickey Thompson ET street radials. They are 27.01" tall. They hook very well. I typically drove on BFG Radial TA on the street, but this year I went to Nitto NT555R extreme drag radials for every day tires and they hook well on the street. I am considering leaving them on for the track. They are P275/60R15 and are 28.00" tall. What will this do to my times? Faster or slower? I run 4.10 gears and I have an overdrive transmission, but i never get into overdrive in 1/4 mile. Curious to hear the comments.
 
Bring them both and experiment. That's the only way to know for sure what works best for your car, at your track...
 
all depends on the engine combo..

taller tires will lower the rpm through the traps but may hurt the 60' time..

only one way to find out for sure..:)
 
Geometry dictates that a taller tire will have a bigger footprint than a shorter tire, widths being the same.
 
rklein383 said:
Geometry dictates that a taller tire will have a bigger footprint than a shorter tire, widths being the same.
Click to expand...

That would be true when comparing the same brand and style tire in different sizes. When different tire compounds are used by different manufacturers, that throws another variable into the equation. Of course he still has a bigger footprint with the taller tire, but the compound of the shorter tire may be superior and provide a better launch.
 
I run low 12's now with the MT. I am definitely going to try them both, but I figured someone must have done this at sometime. 408 stroker - 500hp, 200-4R transmission, though it never gets into overdrive on the track. I just had the transmission rebuilt and I went with a higher stall converter. I went from 2500-2800 to a PCT custom built 3500 stall. I wonder what that will do?
 
rklein383 said:
Geometry dictates that a taller tire will have a bigger footprint than a shorter tire, widths being the same.
Click to expand...

The widths are not the same. 255 and 275, and the height is relative to the width. the taller tire will definitely have a bigger footprint. Though what that has to do with my 1/4 mile times, I don't understand. The shorter tires never spin - they hook perfectly until the track conditions deteriorate around the sixth or seventh run.
 
new converter should help 60'..

as far as going in to OD at the track goes. thats the last thing you want. should go through the traps at the top of your rpm range.
 
higher stall may cause tire spin. if she was dynoed, at what rpm was peak power, and at what rpm are U crossing the finish line. 500 hp should be in the 11s. have U done shift rpm testing? taller tire does not necessarily equal a bigger footprint-other factors are vehicle weight, tire width and air pressure and wheel width
 
Marcohotrod said:
higher stall may cause tire spin. if she was dynoed, at what rpm was peak power, and at what rpm are U crossing the finish line. 500 hp should be in the 11s. have U done shift rpm testing? taller tire does not necessarily equal a bigger footprint-other factors are vehicle weight, tire width and air pressure and wheel width
Click to expand...

Peak horsepower is 5900 rpm. Peak torque around 3900 - 4300 rpm. Never looked to see what the rpm was at the traps. I have never done rpm shift testing. Don't even know what that is.
 
I have experimented with shifting. I tried shifting sooner to take advantage of torque at lower rpms, but in the end it seems to get the best times when I shift instinctively. It's hard to watch the tach when you're hammering down the track anyway.
 
where is your tach located? never had a problem watching mine.. only way to be consistent it to shift at the same point every time... i used to shift a5800 and go through the traps at 6ooo rpm..
 
It's right in front of me, left center. I could try watching, just a lot of room for error at full acceleration or 100 mph plus. I usually hit the traps at 114 or so. I'm hoping for better launches tomorrow. My line locks won't hold, so I was power braking last year and it made a big difference. Now that I'm a little more comfortable with it I think I'll do much better. I programmed some different timing curves to try with the higher stall. I will change the curves a few times just to see what works best. I love that programmable MSD box.
 
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