Since I don't go fast but desire low end torque, I'm considering dropping from 17" to 16" tires. Howver, that means my speedo and odometer will read higher/farther than is the case.

Knowing that different style MINIs can come with different size tires, one would think MINI has a way to easily set the tire size in the speedo/odo to provide the correct readings. Is this true and can tis be adjusted to reflect a tire size change?

 

since you change the tire profile when you change the diameter of
the wheel you shouldn't need to recalibrate.

 

I use this tool all the time when trying to figure out tire/wheel ratios and what affect it will have on my speedo. Check it out here.

The tool is written in Java, so make sure you have the JRE plug-in for your browser.

 

OE 205/45-17 ~ 195/55-16 ~ 175/65-15
They are all roughly the same height.
There's no easy way that I know to change the speedo gearing.

 

Now I am confused. Folks in other threads kept talking about giong to smaller tires for better torque but speedo was off...now you're saying they are the same. My head is about to explode...

 

You CAN go to a smaller aspect ratio in a smaller tire - i.e. a 195/50-16 tire will be 2.5% smaller. A 195/45-16 is 5.6% smaller.
But just changing rim diameter doesn't automatically give you a smaller TIRE diameter.

I use this calculator

 

My bad...I wasn't clear. However, you will note I said smaller tires and not smaller wheels.

 

Actually, you said 17" tires to 16" tires. No mention of aspect ratio.

 

...same idea here:

So if I go from my 205/45/17's to a set of 185/65/15 winter tires/wheels - then I should have no issues?

thanks in advance!

 

The new tire combo calculates out to .8% larger, so when your speedo reads 60, you'll be going 60.5.
Convention is to stay within 2% of the standard diameter, so you're set.

 

Not really true, depends on which wheels and which tires.

If you want more responsive accleration and faster braking then select wheels and tires that weigh less and rubber that offers more grip and maybe larger contact patch within reason.

If you want the least speed/odo error then go with any tire size that is close to stock tire diameter of 24.4" or similar.

Smaller tire diameter helps to simulate lowered gearing and usually helps acceleration but may cause some speed error and may wear out the tread quicker.

17" wheels are 17x7 and tires are 205/45-17.

16" stock wheels are 16x6.5 and tires are 195/55-16.

Aftermarket wheels can be much lighter than stock wheels and tires can vary-

For 17" rims
215/40-17 is smaller than stock
215/45-17 and 225/45-17 are larger than stock

For 16" rims
205/50-16 is smaller than stock
205/55-16 is larger than stock

You cannot reset how your MINI displays speed and odo readings. You can use tires that are 1-3% from stock specs for the least variance and that is usually what we end up doing.

 

Thanks much!!

 

Or....you can get a Scangauge II or similar OBDII reader/display. One of the things that it can display is vehicle speed. It is the real ECM reading, not the "faster" value displayed on the speedometer. It can also be adjusted for different size tires, so you can see your real speed.

Scott
90SM