Hello all,

Looking for a little information regarding tires for the R56. I have done a little research and understand the R56 is known to have the speedometer off depending on tire size.

With all the optional tire/wheel sizes offered what are the stock tire sizes offered by mini for the S, JCW and wheel dimensions?

What tire size corrects the speedo calibration?

Lastly are all tire sizes e.g. 215/45 17 have the same dimensions or do they very by manufacture?

Thanks for your patience!

Cheers!

 

In my experience, even factory setups are + by 2 mph on the speedo. I have confirmed this on 2 cars by the current speed radars posted on local streets before intersections.

 

There is an entire forum dedicated to Tires, Wheels and Brakes: https://www.northamericanmotoring.co...and-brakes-36/

 

In addition, no matter the diameter of the wheel, the profile or height of the corresponding tire retains the outside diameter of the setup, this retains the speed calibration as set by the factory.

 

I'm running 215 45 17 and my car is 2 mph slower than the speedo, verified by my phone gps and my garmin car gps.

 

Mine is also 2 mph slower.

 

I also noticed I'm 4 mph slower (215/40x17).

 

Mine is 2mph slow at 65mph. It was 4mph slow before I changed to 215/45-17 Continental DWS.

 

To answer your question:
Wheel offset tire model
61/2JX16 ET:48 195/55 R16 default MCS, optional on Justa
7JX17 ET:48 205/45 R17 default JCW, optional on MCS
7JX18 ET:52 205/40 R18 optional on JCW

All OEM speedometers are calibrated a bit conservative, to allow you to match or stay below the speed limit even net of manufacturing variances. 0-5 mph lower than true @60mph is customary.

You can experiment with alternative tire sizes, with the goal of preserving the overall tire diameter the same. That way the gearing and acceleration will not get negatively impacted.

For example, you can go with 205/55-16 wheels instead of 195/55-16 OEM size and pickup additional 1.77% larger rolling diameter. That would result in 1.77% higher actual speed vs. indicated, or 61.06 mph vs. indicated 60 mph if your speedometer was originally dead on. The car will accelerate marginally slower having, effectively, increased gearing by 1.77%.

Similarly, you can go in the other direction and 225/45-16 tires on 16" rims and drop the rolling diameter by 1.93%.

In reality, people usually explore the available tire choices in various sizes by looking at www.tirerack.com. Not all sizes have a lot of good performance tire choices, so make sure not to corner yourself into a crappy tire selection just because you fell in love with a certain mathematically attractive tire size

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Nearly every modern car on the road today has a "conservative" speedometer that is a slight percentage higher than your actual travelling speed. It's not specific to the R56. My 1990 3 series was off by a larger percentage than my R56 is, for example.

If you are asking questions about tires, you should be focused on performance. What your driving habits and needs are vs. what tires compromise best to you. performance vs cost, handling performance vs wet traction. Should I run dedicated performance tires and snows, or should I find the right all season.

The only questions about size should be based on ride quality and performance, not "correcting" a factory "defect" that just about every single car on the road today has. That's just silly.

 

You can not entirely correct the speedometer error with tire size. Treadwear over the life of the tire will cause the speedometer accuracy to change as much as two percent.

Tire size is nominal. It varies by manufacturer, by model, and if you get real picky, by each individual tire.

 

Thanks all for the information, there are a lot of factors to consider when deciding on what tires to purchase.

I'll be looking for a "all summer" tire, as I have other vehicles to drive.

Cheers!

 

Ill say this, for a super high performance summer tire, I was impressed with my re11s wet traction. Best handling street tire.I've ever owned.

 

+1 for RE11s - loved them as my previous set.
Went with Michelin PSS's on my wife's car - fantastic street summer tire as well. Maybe fractionally less traction on dry vs. softer ride and marginally quieter.

Neither will give you an unfair advantage on autoX (there are louder and harsher riding tires that are fractionally stickier in the dry), but both will get you 95% there. The skill can make up the difference the rest of the way, unless you are competing at nationals.

a

 

The computer on the Minis is deliberately adding to your speedo. There is a setting in the profile that turns this off. If you want to correct your speedo, look into NCS Expert - don't muck with your tires to try and fix it.

 

I find 205/55-16 makes the speedo pretty accurate.