Tyre Size V's fuel consumption

[Cruza]

Just a quick question that i'm sure most would be able to answer without any trouble...

If I go to a small tyre, say a 32x11.5 from a 33x12.5 will that increase millage? Would it also work on the same theory that....The bigger the tyre the slower the accelleration, but higher top speed on the highway? And vice-versa???

thx

N

 

[Doc]

Yes, even decreasing the size of the contact patch, say going from a 12.5 to a 9.5 width would help out with milage.

 

[HZJ60 Guy]

I agree with Doc, but it is more complicated than that.

Your vehicle was built around a specific horse power and torque curve. When you change tire size without changing gearing to match the change you effect those curves. If you go smaller (like some Team Teriyaki rice burners do) you'll be reving higher at all speeds and will have to drive slower at times. If you go larger (like us krazie 4x4 nuts do) then you'll be down on power and torque and will have to use lower gears. Sometimes you wont even be able to use 5th (4th with an auto)

You can make smaller adjustments and not have problems, but those guys going to 36'+ tires on stock gearing are nuts.


TB

 

[lovetoski]

My guess is that given the shape (non-aero) of a cruiser, the biggest impact on milage would be due to speed. Not that tire size/width wouldn't have an impact as Doc mentions, just that speed per se is probably the biggest factor.

I keep thinking of doing an experiment during my drive to/from Seattle and Portland, but so far I don't want to slow down...

Best Regards,

 

[Cruza]

Thanks Guys,

Does anyone have the specs as to what the 60/61 series came out with?

When I bought her she had 33x12.5, now I know this wouldn't be standard, I also thought the conversion between 32x11.5 would be "close" to what it was as standard?

Thanks Heaps

 

[HZJ60 Guy]

Well let's see. 3.73 ring and pinions, a 1 to 1 4th gear and I'd guess 27 to 29" stock tires.

Do that math.



TB