Hello. I'd been planning on replacing the stock 205/45-17 runflats with non runflat tires of the same size. What are the pros and cons of going to a wider tire? Also I see that not all replacement tires are the same height. What are the pros/cons of going with a shorter/taller tire?

Thanks.

 

Wider tires, Pro= bigger contact patch, improved grip, Con=heavier

Tire height will effect your speedometer and odometer, I try to keep it as close as possible but will err a tiny tiny bit going taller just because I don't want to cut down on the sidewall on the already thinner 17" tires.

 

If you want to keep everything the same as stock performance and handling then choose the stock 205/45-17 size. You will have less tire selection if you do. The MINI designers worked with this size tire so speedometer and odometer are based on that size. If you get any tire with diameter smaller or larger you get a little error but if it is within 3% of the stock 24.3" size then it's OK. If you can live with the error then it's also OK.

2002-2004 MCS came with manual transmission that had taller gears which are OK for street use and good for highway economy but not as good for performance driving on the track or for autocross. So what many people did was to go with tires that had a smaller tire diameter which effectively lowers gearing for performance reasons. A good example is 215/40-17 or 205/40-17. As long as the load rating for each tire is about 84 which is stock then it's fine to have a slightly smaller tire. Many of these tires weigh the same or less than 205/45-17.

But if you keep the sidewall 45 series or larger and make the tire wider like 215/45-17 or 225/45-17 then you get a heavier and wider tire with tire diameter greater than stock. This can close the wheel gap but also create rubbing issues on any lowered suspension MINIs. Wheel offset becomes important as less offset moves the tire closer to the outside of the car and taller tire and rear lower wheel arch plastic may rub under full load or with dips in the road surface.

Tire selection is much better in 215/45-17 and this will work OK with stock suspension so it is very popular. 225/45-17 is a good size but a little too tall for the MINI. It barely fits the stock suspension. Those with coilover upgrades can adjust ride height so it's not that bad.

215/40-17 is harsher for street use since sidewall is a shorter 40 series- stiffer and less comfortable. Also stiff so if you hit a pothole you transmit shock to the rim or suspension and could damage things if not careful. 40 series tires can cost more than the stock size or 215/45-17.

Here is an example of one tire in different sizes-

BF Goodrich g-Force T/A KDW 2, Ultra High Performance Summer tire
300 treadwear Y speed rated

205/40-17 $130 fits rims 7-8" wide, perfect for 7.5" rim, 23.5" tire diam, 84 load rating, 22 lbs each.
205/45-17 (stock size) $120 fits rims 6.5-7.5" wide, perfect for 7" rim, 24.3" tire diam, 87 load rating, 22 lbs each.

215/40-17 $134 fits rims 7-8.5" wide, perfect for 7.5" rim, 23.7" tire diam, 87 load rating, 22 lbs each.
215/45-17 $137 fits rims 7-8" wide, perfect for 7" rim, 24.6" tire diam, 91 load rating, 24 lbs each.


225/45-17 $131 fits rims 7-8.5" wide, perfect for 7.5" rim, 25" tire diam, 90 load rating, 24 lbs each.

205mm wide is a good blend of traction, handling, and moderate rolling resistance. For dry and wet traction 215mm or wider would be good but the tire has to fit and not rub the suspension parts or fenders. In the snow you want tires that are more narrow 195mm or less to cut through the snow. For highway driving you want a tire that offers less rolling resistance for best mpg, 195mm or less is better even down to 175 or 185mm for any MINI on a smaller diameter rim like 15".

 

one more thing to consider... check the mfg. width and rolling diameter of a specific tire... as they change.
the weight of some tires is much greater than others (bad)

generally speaking:
the wider the tire, the more contact patch, the faster you can corner, accel. and brake.
but the down side is worse ride, and worse snow traction.

taller skinnier tires work best in snow
typically you'd drop a rim size and increase sidewall (called -1 sizing) to keep the same rolling diameter.

a +0 is the same size rim as what you started but with wider CP.
+1 is 1" larger rim, with smaller aspect ratio (shorter sidewall) and so on...

I can send you a spread sheet I made showing this (it helps figure out what will fit with min. change to speedo/odo)... as you need to keep the rolling dia. the same.

 

A larger contact patch is a myth. The overall contact patch size is the same between different profiles and widths on the same car. As the width goes up and the aspect ratio goes down the shape of the contact patch changes. A tall narrow tire will have a long and skinny contact patch while a short wide tire will have a wider contact patch thats not as long.

Stolen from Tire Rack site..

 

Wider tires may give you less miles per gallon, from my experience.

But they look better!

 

wider tires require a wider wheel for better appearance and sidewall stability too...

dont go too wide unless you really need it.

 

A CON not previously mentioned: wider tires seem to increase the MINI's tendency to tramline at highway speeds, especially over grooved or uneven surfaces.

Regarding previous coments regarding the tire/wheel package used during development: I remember reading that the sport suspension plus was tuned around the standard 16x6.5/195/50 R16 package, and that the 17" option was added for aesthetic reasons. I came across this info on NAM ages ago so I can't speak to the reliability.

 

I think the 16" standard was 195/55, not 195/50.