[sum_weirdo]

Just bought my 2006 4.0 Mustang yesterday and I got a Hypertech programmer bundled along with it. Been reading the instructions for it just now and I know it's gonna ask if I want to program a different tire size than stock. Now I could just say no to that except I don't know if my Pony Package tires are taller than regular stock...in which case the computer might have already been altered to accept them and I should make sure it stays that way.....am I making sense?

[Stanger78]

When it ask you just say yes and program whatever tire size you are running... Thats what i would do
I hope that clears up some confusion for you.

[mrjimmy]

my sct just wanted rim size,I think,so I put 17" and also it wanted gear ratio,so I entered that to.
That part makes a difference for calibrating the speedometer.
Hope this helps

[sum_weirdo]

Well yeah but it asks for the tire height in inches, not the size. I haven't got a measuring tape handy, just wondered if anyone knew.

[sum_weirdo]

Sorry didn't see your post Jimmy. But yeah mine's not interested in rim size, it wants the whole height of the tire.

[stlwagon]

What size tires do you have on there?

[sum_weirdo]

Just looked it up on Ford's website, unless the size was different in 2006 the tires are 235 / 55ZR17.0 I'd check but the car's a block away right now :P

[stlwagon]

235-55-17s are 27.18" tall.

[sum_weirdo]

Awesome. Thanks man.

[ponyexpress1573]

stl is close
If anyone ever wanted to find out on their own here is the formula

235/55/17 is my example

235 width in tread in Millimeters

55 percent of width of tread side = wall height also known as aspect ratio

17 rim size in inches (go figure mixing inches and Millimeters)

ok now the math

235 X .55 = 129.25
129.25 x 2 = 258.50
258.50 x .039 = 10.08 this is the conversion mm to in
17 + 10.08 = 27.08 total tire height

[FYouGitive]

Here's a comparo-chart for tire sizes I have used on my V6. Make your own here:

Tire Size Calculator - tire & wheel plus sizing

[sum_weirdo]

Cool. Does look as though the difference is too negligable to make a difference no matter what I do, especially since the programmer only adjusts in 1/4 inch increments anyway. Probably set it at 27.25.

[sum_weirdo]

Or I could just say no to that queston I guess. If there is already a more precise calibration in there then the programmer might leave it alone.

[FYouGitive]

Originally Posted by sum_weirdo

Or I could just say no to that queston I guess. If there is already a more precise calibration in there then the programmer might leave it alone.

I'll bet you're right. Any programmer/tunerdude worth his salt will take advantage of everything within the limits of the machinery, and not mess with non-essentials.

I've read that some tuners use wheel revolutions per mile as the adjustment parameter. Seems to me I recall five wrpmile was the smallest interval that could be accommodated. I wonder (maths-challenged as I am) if that is a finer or grosser adjustment than a quarter-inch tire-diameter difference?

[stlwagon]

Originally Posted by FYouGitive

I'll bet you're right. Any programmer/tunerdude worth his salt will take advantage of everything within the limits of the machinery, and not mess with non-essentials.

I've read that some tuners use wheel revolutions per mile as the adjustment parameter. Seems to me I recall five wrpmile was the smallest interval that could be accommodated. I wonder (maths-challenged as I am) if that is a finer or grosser adjustment than a quarter-inch tire-diameter difference?

SCT tuners use revs/mile to calculate. Problem is they only use 5 rev increments so it's tough to get it 100% accurate.