[coachhomer]

I have a 2002 f-250 4x4 with no lift. I want to change my rims to 17x8 welds, but what tire size should I run? It seems to me that the options available for the BFG a/t are...

285/70/17
265/70/17

will the 285 fit?

I am running 285/75/16 now with no problems.

Thanks for any help and additional info.

Scott

 

[HoustonPSD]

This is how you determine overall tire height. It comes in handy for situations like you are asking about.

1. 285/25.4 = 11.22
2. 11.22*.75 = 8.415
3. 8.415*2 = 16.83
4. 16.83 + 16 = 32.83

1. Here you are dividing 285 (your tire width in millimeters 285/75/16) by 25.4 to get your tire width in inches (25.4 millimeters per inch)
2. Here you are taking your tread width of 11.22 inches and multiplying by the tires aspect ratio (285/75/16). The aspect ratio is a percentage. It defines the height of the sidewall as 75% of the tread width, thus .75.
3. Here you are taking your sidewall height of 8.415 and multiplying it by 2...because you have a sidewall above and below the wheel.
4. Here you are adding the combined sidewall heights of 16.83 with the wheel circumferenc (285/75/16) to get your overall tire height of 32.83.

285/25.4 = 11.22
11.22*.7 = 7.854
7.854*2 = 15.708
15.708 + 17 = 32.708

As you can see they are very close in size and should work fine. Hope that helps a little bit.

 

[DecreasingDave]

OK...To make this easier by far.

285/75/16

The first number (285) is the width of the tire

The second number (75) is the aspect ratio of the tire. Aspect ratio is the "percentage" of the width, in this case, 285.

The third number (16) is the rim size.


Now, for the hard part.

If you want to keep the same size tires (height wise) but want to increase rim size (as you do), then you want to decrease your aspect ratio (i.e. 70).

Therefore, your new size would be 285/70/17. This would keep your tires at the same height as you original tires.

Now, manufacturers overall sizes will vary as size changes. Even within the same manufacturer. It may be off some, but not much.

Hope this helps,
Dave

 

[HoustonPSD]

[ QUOTE ]
OK...To make this easier by far.



[/ QUOTE ]

Didn't realize simple math and an explanation of how it truely works was too diffcult. The knowledge may come in handy in the future...it has for me time after time when working with my Mustangs...just trying to pass it along.

 

[DecreasingDave]

[ QUOTE ]
[ QUOTE ]
OK...To make this easier by far.



[/ QUOTE ]

Didn't realize simple math and an explanation of how it truely works was too diffcult. The knowledge may come in handy in the future...it has for me time after time when working with my Mustangs...just trying to pass it along.

[/ QUOTE ]



Whatever.....