Ok, I googled and googled. Read a good many pages, and what I've basically come up with is the following:

Moving from 16" to 17" rims, the ONLY plus is looks.

The major negatives are, much bumpier ride, and handling will diminish.

I understand the bumpier ride (with the run flats) however I don't understand the ride diminishing.

For those of you who have done this, did your handling diminish? Did you have to have the dealer tell the computer that you now have 17's? Or will the speedometer/odometer automatically adjust?

Thanks!

 

Curious as to what the answers are as well.

 

Less rubber between the road and the wheel and the car itself.

 

But aren't the 17" tires wider (side to side)?

 

I believe what they are referring to is the fact that with a 17" wheel you usually end up with a much lower profile tire - less height on the side wall. The 'skinny' side wall provides less rebound when you hit bumps and if you add the stiffness of a run flat, some (many) find the ride too hard.

Handling decrease? Hmmm - more subjective - but as you note the typical 17 set up is a wider tire. What I CAN tell you from experience is that my MINI on 17's trammeled a LOT more than I do now on 16's. BUT we are also comparing a GEN1 on 17 to a GEN2 on 16 - both S hardtops

 

Does the dealer need to tell the computer that you have changed sizes?

 

Width is up to you, and generally based on wheel width, not diameter. You may be limited due to the aspect ratio available in the given tire size, but a 10mm difference in width (even 20mm) is not going to kill you either way. In fact, I generally prefer the slightly wider contact patch and its benefits vs. the skinny tire benefits.

Our OEM 16" wheels came with 195/55 tires. With the factory 16" wheel you can go down or up in width, down to 175/60, or up to 215/50.

The general idea is to match the diameter of the wheel with the factory size.

Example - 195/55-16 is ~24.45" tall.
175/60-16 is ~24.27" tall
215/50-16 is 24.46" tall.

Go to a 17" wheel, and you can do 205/45 or 215/45. Those are:

205/45-17 ~24.26" tall
215/45-17 ~24.62" tall

So you will basically keep the same height (~.25" difference, or about 1% change in diameter from OE) so the speedometer and odometer will not be affected enough to warrant any concern. In fact, most mfg's will have their speedometers calibrated down by 1-3% for margin of error/safety. You can check with a GPS, but I wouldnt worry.

You will got to a shorter sidewall, but because the sidewalls are so stiff on run-flats, you may not notice a difference if going to normal tires.

I switched to a "xtra load" sidewall in a standard tire, and thinks it rides a little better than the 16" runflats

As to trammeling - that could be tire tread design, suspension design/geo (if different between 1st and 2nd gen) or other items as much, or more, than wheel size. Width will affect it some, but diameter (especially with being so close to OE) should not have much affect.

 

Scottt: The 17" OE wheel is only .5" wider than the 16" OE wheel (7" versus 6.5"). A fairly popular tire size switch for 16s is from the OE 195/55/16 to a 205/50/16. That provides the same tire width as the OE 17" tire, with very little reduction in tire diameter. Thus, all else equal, it should provide a very slight improvement in lateral grip, at the cost of a very slight reduction in ride comfort. Of course, a fairly popular tire size switch for 17s is to the 215 width.