O.K. here's a theory.

In choosing between 16 and 17" wheels, many people find that the 16's offer a better ride and rim protection but I wonder if some of the 17's with the XL sidewalls will offer similar protection. Obviously the 16 will still be somewhat smoother.
Also regarding the tramlining of a 17" wheel, doesn't the 16 still run the same width ie. 16X7 or 17X7.

And one last thing. To prevent rubbing issues many seem to move to a 16", but I've noticed that overall wheel diameter is the same between a 205/50 16 and a 205/45 17. Or at least VERY close. Doesn't this negate the benefits of the 16" wheel.

Please satisfy my curiosity...

 

Ask Minihune the tire and wheel expert.

 

To keep the same diameter, a 17" tire will have less sidewall. You can go with a taller 17" tire, but then you'll be increasing diameter, making the speedo less accurate (it'll read slower), and partly negate all of the reason for going with the 17" (aesthetics).

I'm currently running 205/50/15s. Last year I ran 205/50/16s. The new ones are a full inch shorter. My speedo is off 6-7%. Can it be done? Sure. Why? *shrug*

Oh, and you're not mentioning weight savings. My 15"s are 11lbs, the old 16"s were 16lbs, the smaller tires are lighter, and all of the weight is closer to the hub.

 

Both 16" and 17" wheels and tires can work for the MINI.

17x7 rims usually require 205mm or wider tires with 40 or 45 series sidewalls.
vs
16x7 rims with 195 or wider tires and 45, 50, or 55 series sidewalls.
The taller sidewall can offer tires that allow for more comfort.

XL sidewalls are usually stiffer to allow for more load rating and that usually means a more firm ride if everything else is equal.

Tire design and contruction are big factors in comfort as well so some tires are very good on handling and poor on comfort while others offer less good handling but very good comfort.

Rarely there are some tires that offer very good handling and very good comfort but they might cost more or wear faster or come in limited sizes. Oh well.

Better ride and rim protection
Ride comfort is determined by many factors- suspension, tires, tire size, rim size, alignment, road surfaces, etc.
Rim protection is better with sturdy rim construction (maybe moderate weight), tires with sidewalls that absorb some shock, suspension that is not too stiff, and not hitting potholes at speed.
Lower sidewalls may not offer as much rim protection.

Tramlining
Is avoided by picking tire sizes that are not too wide for a given rim (correct fit), trying to spend less time driving on concrete highways with grooves, and picking tires with tread design that doesn't favor tramlining.

Rubbing issues
Is avoided by picking the right offset for a given wheel size and right sized tires that are not overly tall or wide for a given suspension setup. Lowered cars have less clearance and wheels with smaller offsets position the wheel farther to the outside of the wheel wells. The rubbing area is usually the outer treads of the tire in the rear with the inner edge of the rear wheel arch plastic.

 

Thanks for chiming in everyone!
Minihune I understand what you are saying and appreciate your lesson in tires/rims. However I think I may not have got my question across properly, my bad.
In an earlier post I was asking about the compatibility of using an Ultraleggera 17"wheel and a 215/45 tire, in which I had quite a few replies (your replies as well) Some of these replies brought upon questions of concern about rubbing, lowering and rim protection. Others suggested the use of a 16" wheel and a 205/50 tire. This definatly peaked my interest, however when I looked further into it, I found that the OD of tire assembly was not much different than the 17" with the 205/45. If I lower the car with either assembly I should assume that both will rub. Then I looked into tires and realized that there is such things as xl rated tires on the 17's which I thought may add a bit of protection to the rim.
Yeah this sounds like I'm really trying to find 16" performance in a 17" wheel.
Anyway thanks a bunch for the responses.
Cheers

 

No, XL has not much to do with rim protection, it refers to strengthened sidewall to handle a greated load.

Lowering any car will decrease clearance with any tire. Stock tires or smaller which are 205/45-17 and 205/50-16 are OK and even smaller tires like 205/40-17 and 215/40-17 are even more likely not to rub even on lowered MINIs but for any stock suspension they will increase wheel gap so you must plan ahead if you have not done your lowering yet.

If you want a good tire now that you can use but lower your car later then 205/45-17 or 205/50-16 are good choices.

215/45-17 is taller than stock as is 205/55-16 so while those sizes will work with stock suspension they aren't a good choice for lowered MINI unless you can lower only about 1/2 inch or you have ride height adjustable coilovers.

 

Thanks so much Minihune, you da mang!!!
By the way, I just checked out your link "tomo-dachi". Is that your car? If so what tires and wheels are you using there?
regards...