Need help with tire diameter....

[allicedout]

So with this good weather upon us we can see spring is near........ And that means track days are coming up. Now with that in mind I wanted to get some info from the veterans on tire size for the drag strip. Looking at drag radials for strip use and wanted to ask about tire diameter. My cars a 2011 Mustang GT, 6mt with 3:55 gears. Stock tires are 27" in diameter. Am I correct to be looking for strip tires that are smaller in diameter then stock? Some time back fast Ed told me diameter works like gears. I'm just unsure what I should be looking for. As always any help is appreciated.

[fast Ed]

Have you run the car at the strip as is? If so, what gear were you in through the traps, and what were the revs? If not, maybe somebody else here with the same drivetrain package can tell us. Basically, if you're out of revs, and having to lift / feather the throttle or shift up just before the end of the quarter, then you might want taller tires to knock your effective gearing down a bit. If the opposite is true, and you have lots of revs left before the end of the power band in whatever gear you've shifted to well before the end, then shorter tires will be like having a higher numeric ratio in the car, to let it rev higher for a given road speed.


cheers
Ed

[NickD]

Your right in that running a smaller tire will effectively work as running a higher rear gear, I'm planning on putting in 4.10s and running a 26" tire giving me an effective 4.30 rear end.
That said you make a lot more power and the norm from what I see on all 11+ is to run a 28" rear tire. Especially if your running a radial this will help as you have a larger contact patch with a taller tire and you will have !ore sidewall which will hopefully cushion a bit more then a smaller tire which is needed running a stick car.

[bbriann]

Look on internet for a tire / gear ratio / rpm / mph calculator. Lots of calculators for my 2004 , just not
sure if calculator exists for your year.

[12GrabberGT]

http://www.paladinmicro.com/pmicro.php?frm=SpeedInGearCalc.htm

Not sure if this will work for your car but it is a good reference.

[NickD]

Honestly go on s197 forum their is a whole drag racing sub section and you will find tons of info

[Ray721]

Most people run 28" tire on Coyote cars. The MT82 is short geared.

When I was at the strip last year with my stock 19" Pirellis I was going through the Trap at 111mph in 4th and the revs were flirting with the limiter. If I had a better 60' I might have needed to shift to 5th. Or redline through.

That being said I have the Track Pack with 3:73 rear end. So you should be perfect with a 28" tire blasting though the trap in 4th still under good power.

[allicedout]

Thanks Ray, that's the info I was looking for. I ended up getting a sweet deal on a set of BFG DR's on Eagle Alloys. They're 26" in diameter and I've got 3:55's so if I'm not mistaken I should probably be close to a 3:73 in the rear? Anyhow it was a deal so let's see how it works out in the spring....

[Ray721]

Thanks Ray, that's the info I was looking for. I ended up getting a sweet deal on a set of BFG DR's on Eagle Alloys. They're 26" in diameter and I've got 3:55's so if I'm not mistaken I should probably be close to a 3:73 in the rear? Anyhow it was a deal so let's see how it works out in the spring....
Should be fine. Youll proably be at the very top of 4th through the trap. Good luck!