tire diameter?

05-09-2001, 04:18 PM

225/50-15 whats my tire diameter in inches? And the formula?

------------------
Ford Mustang -87 With K&N filter and walker exhaust.14,61 and 95,5.
4,10 rear before june 2001.

jimberg · 05-09-2001, 04:30 PM

It's width times aspect ratio divided by 1270 + wheel size.

(225 x 50) / 1270 + 15 = 23.86.

------------------
351W 89 Mustang GT Convertible

05-09-2001, 07:55 PM

Jimberg, that is a good and easy formula. Is the 1270 a constant? Just wondering were that (1270) came from.
I usually do a rough figure, 225/25 x .5 x 2 + 15 = 24. The reason that is rough is that 25mm is not exactly an inch, its 24.??. Your formula looks to be exact and much easier.

------------------
Rick
My 89lx(updated 2/21/2001)
My 97 Cobra

jimberg · 05-09-2001, 08:11 PM

The 1270 is half of 2540. There are 25.4 mm to an inch. Since I don't treat the aspect ratio as a percentage, I make up for it in the conversion factor. Also, since dividing by 2540 would give you the sidewall height, I divide it by 2 to get 2 times the sidewall height. Then you just add that to the wheel height.

05-09-2001, 09:22 PM

Ahhh... the 1270 isn't a constant. I should have been able to come to that conclusion. So the formula is tire width divided by ratio times 2 plus rim size.

05-09-2001, 09:27 PM

Actually I don't know what I'm thinking. Its the same formula you where just more exact and made it simple for him...

jimberg · 05-10-2001, 09:44 AM

It's a simplification of the formula:

( ( <Tire Width> * <Aspect Ratio> / 100 ) / 25.4 ) * 2 + <Wheel Diameter>

1270 is a constant.

05-10-2001, 11:29 AM

Thanks

05-09-2001, 04:18 PM	#1
joakim Guest Posts: n/a	tire diameter? 225/50-15 whats my tire diameter in inches? And the formula? ------------------ Ford Mustang -87 With K&N filter and walker exhaust.14,61 and 95,5. 4,10 rear before june 2001.

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05-09-2001, 04:30 PM	#2
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	It's width times aspect ratio divided by 1270 + wheel size. (225 x 50) / 1270 + 15 = 23.86. ------------------ 351W 89 Mustang GT Convertible

05-09-2001, 07:55 PM	#3
rbatson Guest Posts: n/a	Jimberg, that is a good and easy formula. Is the 1270 a constant? Just wondering were that (1270) came from. I usually do a rough figure, 225/25 x .5 x 2 + 15 = 24. The reason that is rough is that 25mm is not exactly an inch, its 24.??. Your formula looks to be exact and much easier. ------------------ Rick My 89lx(updated 2/21/2001) My 97 Cobra

05-09-2001, 08:11 PM	#4
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	The 1270 is half of 2540. There are 25.4 mm to an inch. Since I don't treat the aspect ratio as a percentage, I make up for it in the conversion factor. Also, since dividing by 2540 would give you the sidewall height, I divide it by 2 to get 2 times the sidewall height. Then you just add that to the wheel height.

05-09-2001, 09:22 PM	#5
rbatson Guest Posts: n/a	Ahhh... the 1270 isn't a constant. I should have been able to come to that conclusion. So the formula is tire width divided by ratio times 2 plus rim size.

05-09-2001, 09:27 PM	#6
rbatson Guest Posts: n/a	Actually I don't know what I'm thinking. Its the same formula you where just more exact and made it simple for him...

05-10-2001, 09:44 AM	#7
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	It's a simplification of the formula: ( ( <Tire Width> * <Aspect Ratio> / 100 ) / 25.4 ) * 2 + <Wheel Diameter> 1270 is a constant.