Tire Guru Question

[FJRottie]

To any tire genius:

Ford Ranger FX4

I have 31 x 10.5 R 15 Tires (High Flotation sizing) which are about 267 / 76 R 15 (Metric)...I think.

Thinking about mileage, looking to go to 255 / 75 R 15. (minimal handling difference)

I know it will affect the speedo since the truck is calibrated with the first tire size I mentioned. It will be minimal.

Could I go smaller yet ? (I'm thinking too much smaller would be bad for speedo)

Should I change the rim size and go for 255 / 70 R 16 ?

Should I even bother ?

Burning the midnight oil.

 

[Just Plain Dave]

To any tire genius:
Ford Ranger FX4

I have 31 x 10.5 R 15 Tires  (High Flotation sizing)  which are about 267 / 76 R 15 (Metric)...I think.

Thinking about mileage, looking to go to 255 / 75 R 15. (minimal handling difference)

I know it will affect the speedo since the truck is calibrated with the first tire size I mentioned. It will be minimal.

Could I go smaller yet ?  (I'm thinking too much smaller would be bad for speedo)

Should I change the rim size and go for 255 / 70 R 16 ?

Should I even bother ?

Burning the midnight oil.

After studying your questions very closely and taking all factors into consideration, working out the mathematical equations and applying physics formulas, I am absolutely definitely sure that maybe you should. (If you really want to) (or maybe not) :blink:

Happy New Year

 

[kaitsdad]

To any tire genius:
Ford Ranger FX4

I have 31 x 10.5 R 15 Tires  (High Flotation sizing)  which are about 267 / 76 R 15 (Metric)...I think.

Thinking about mileage, looking to go to 255 / 75 R 15. (minimal handling difference)

I know it will affect the speedo since the truck is calibrated with the first tire size I mentioned. It will be minimal.

Could I go smaller yet ?  (I'm thinking too much smaller would be bad for speedo)

Should I change the rim size and go for 255 / 70 R 16 ?

Should I even bother ?

Burning the midnight oil.

Clicky

I've found this to be helpful -

 

[radman]

More to it than the speedo. A speed sensor feeds info to the ECM, which uses vehicle speed and other inputs to determine shift points, injector pulse width, egr openings etc. manufacturers like to keep things simple, and will try to match tire diameters throughout the range of availability so as to use the same calibrations throughout. Check to see what was available from the factory, and you may finnd a nice, tall, skinny tire that will work well in the snow and work with present settings.