I have an 08 Cabrio with the "wonderful" CVT transmission. Speedometer error is almost 10% optomistic. The car came with 175/65-15 tires. It hydroplanes and seems to sit low with the continental tires on it. I want to go to a larger size of Michelin. Can I go as far as 195/65-15? The wheels are either 5.5 or 6.0 inch. This would help the speedo error and hopefully hydroplaining. I realize it would hinder the power a little but the extra ground clearance might help with leaving road hazards on the road.

 

I would ditch the 15's in favor of 17's. A nice 225/45/R17 would fill the wheel well out nice while still having a decent enough sidewall for a not to harsh ride.
personally, I like my ride on the harsh side (proforms better on twisties) so plans up to 18's are in the future

 

I researched the 175/65-15 speedo correction problem. There are a lot of smart folks and posts in this tire group to look over. Here are some things I noted.

The 16 and 17 inch wheel cars seem to be much more accurate on speedo and perform well. I think a larger wheel and tire is a potentially good solution for someone with $$ to upgrade both. (Not me)

Mini selected the 15" rim and 175 width for a reason. I suspect they were inexpensive (in volume) and performed overall very well. The reason I qualified the price comment is because stock tire replacements are over $70 each on Tire Rack. All manufacturers and styles are over priced IMO. You can go up one size to 185 and save almost $30/tire (Kuhmo Solus KH18 $42) - more rubber, more longevity, for way less money.

What about performance? At 16 lbs, the stock Continental tires are about as light as one can get. Light has a lot of advantages, especially in "unsprung" weight. One author contributing to this topic in another post compared light tires to lightweight running shoes and suggested trying a few laps in hiking boots - the work difference is noticable. Good point. Adding a few pounds to the car doesn't change the performance much, but adding a few pounds to a fast spinning wheel has an entirely different result: decreased acceleration, slower breaking, and worse gas mileage.

Users of 195/65-R16 report that the acceleration and braking, when compared with stock, are not that noticeable, especially if you are a conservative driver - and the bigger tires have the added bonus of smoother ride. Sounds good but read on.

My advice is to ignore the tire calculator. I spent an hour calculating alternative tire sizes only to find out the results were very different in terms of revolutions/mile from what was reported on TireRack's site. Maybe I'm wrong, but years back when I worked in a tire shop, the dimensions of a tire differed by brand - so I belive TireRack's data is more accurate. (I don't have any affiliation with TireRack or any tire company, BTW.)

One of the main reasons, besides driving, that I love the Mini is the insanely-great gas mileage. For me, JustaCooper with a stick at 35MPG combined (measured) and 40ish on the highway hits a sweet spot. As much as the 10% speedo error, and Mini's arrogant non-answer, makes me mad, I'm not willing to give up 3MPG to fix it. So I decided to forgo an estimated 4.3% speedo accuracy improvement with 195/65R15 for gas savings. It's an individual choice that will vary by owner. If you decide to "go big" let us know how it works out. For me, selecting one size larger, 185/65R15, did increase wheel weight from 16 to 18 lbs. Not great, but I like having choice in a buyers market, saving money, and who knows, maybe the speedo will improve a little. I'll let you know when they get mounted.

What makes this forum great is that we are "group smart" so please comment and correct as appropriate.

Dave

 

195/65-15 is too tall for the MINI at 25" tire diameter- it might fit but clearance is reduced. You might rub under a full load or on uneven surfaces.

Your stock rims are 15x6.5" which is the standard MINI 15" wheel size.

Stock tire size is always 175/65-15. Tire diameter is listed at 24".

Stock 16" tire size is 195/55-16. Tire diameter is listed at 24.4".

Stock 17" tire size is 205/45-17. Tire diameter is listed at 24.3".

Try for a tire that will fit your stock 15" rim but offer a tire diameter of about 24.4" or close to it.

The stock 175/65-15 tire size is not usually a good choice for replacements due to less tires that are good for the MINI.

The tire sizes that are common replacements are-

185/65-15 24.4" tire diameter
195/60-15 24.2" tire diameter
205/55-15 23.9" tire diameter

For the purposes of hydroplaning resisitance for normal street driving any of these tires are OK. You need to pick a tire with a tread pattern that is well suited for wet conditions and reduced hydroplaning. Not all wet weather tires are as good in the dry and vice versa. Some are good at both.

If there is any cold weather or snow in your area and you don't have dedicated winter tires then using all season tires make the most sense-

A good example would be in 185/65-15
Bridgestone Potenza RE960AS Pole Position $77 each 400 treadwear 20 lbs

In the same size but with more comfort and longer treadlife for daily street driving (but reduce some crisp handling)
Michelin Primacy MXV4 (Grand Touring All Season tire) $104 each 620 treadwear

If you really want a good wet weather tire
then in 195/60-15
Goodyear Assurance TripleTred $98 each 740 treadwear a little heavier at 23 lbs each
Also see Michelin HydroEdge.
185/65-15 $107 each
195/60-15 $110 each

Note that these tires that handle wet better might not be as responsive for aggressive performance driving in a MINI so some compromise is required.

For more information contact Alex@tirerack.com

There are many options for the MINI in 15" that will work fine.

Figure out a budget, ask yourself if you need All Season tires or not, Determine what you are using your MINI for- only street use or some performance driving, and what are your road conditions- smooth or full of potholes.

If your roads are smooth you can use any size tires. If they are poor then using tire sizes with more sidewall like 185/65-15 is better and this size tire does offer a little less rolling resistance so that mpg can be a big better than with wider tire sizes- a difference of about 2 to 3 mpg depending on how your drive.

 

Just measured the wheels and they are 5.5 wide so the larger (195-65/15) tires are probably out. The manufacturer recommends at least 6" width. Thanks for all of the great info
John
Milton Mini