Currently my ND is running 16 inch wheels and I am considering switching to 17’s. What do I need to consider in terms of making the change in terms of the suspension set up if any?
If you are buying aftermarket i would look into getting a bit wider wheels from stock. Fitting meatier tyres means more grip but wider also means your tyre get closer to the fender.
Wheel offset, buy as close as possible to your stock wheels. The width of the wheels as well as the offset influence how close to the fender your tyre will go. People correct this with wheel spacers but I’d rather not, buying the right wheels with the right offset is much better
As the tyre is part of the suspension, and you will have less tyre wall the ride will firm up a bit but within reasonable expectations.
Because of less tyre wall you will have less tyre lateral deflection that will promote better feeling what the car does if you push it through the corners. For normal driving you won’t notice this
I’m not familiar with the wheels and offset that would fit the ND but as a starting point have a look here. They are based in the USA but their guidance and recommendations are very useful (at least for me)
That your car will be less agile and less fun to chuck round the twisties if that’s your thing…
Some trim levels of the ND came with 17s as standard, from memory their specs are:
I believe the specs for the 16s are:
So you are already somewhat accomplishing @ckleanth suggestion of getting a wider wheel
Although I do know people who have gone wider still!
I have 17" BBS wheels on mine (came as standard on the RF Launch Edition) and then have spacers on top so you either stick with the stock 17 specs of have a play a little with offset and rim width to get even wider and flush with the car body without spacers
Theoretically something specced like this should fit, emphasis on should:
Please do not just go and purchase the above, I strongly recommend doing your own research and checking etc. (the suggestion comes with no guarantee 
)
For example, these will actually have more sidewall than your current tyres (if stock) and make your speedometer over read by ~3% (60mph will actually be ~58mph)
The following websites are always helpful when working this stuff out:
if you still use the stock suspension and a 17" wheel I’m not sure thats the case
I suppose you meant 45mm offset not 25
Past - ND 1.5 Eibachs 16” Geometry set
Past - ND2 2.0 17” Geometry set
Current - ND2 1.5 16”
A major part of moving the 2.0 on was that even after getting the geo set it didn’t provide the same level of agility and fun that the first 1.5 had hence… horses for courses everyone’s perception is different.
I haven’t driven one, my comment was purely on the basis that I wasn’t expecting to have a negative effect. I suppose the tyre is part of the suspension and one needs to judge both as a package. I am genuinely surprised with that.
A lot will depend on what kind of roads you drive on and how you want the car to feel, if I have to drive the MX-5 on a motorway I regard it as a failure 
, B and C roads are the thing though a nice sweeping single carriageway A road is nice too.
For regular motorway/dual carriageway driving then a bit more steering weight and stability might suit better.
Best thing is for someone to try as many options as possible and see what works best based on seat of the pants feedback, 18 years and around 150K miles informs what suits me 
I don’t know if this is the overall perception with the ND but if we leave geometry changes aside changing a wheel/tyre from 16" to 17", a shorter tyre wall would mean a slightly stiffer tyre but it wouldn’t be that much of a difference in the grand scheme of things.
The shorter tyre wall also means you will have less tyre lateral deflection (movement of the wheel laterally in comparison to the tyre). In broad terms this is also a good thing and the expectation is that it promote better feeling what the tyre does when you push it through the corners.
There would be difference in the unsprung mass and I would expect the wheel with the 17" to be lighter - and reducing unsprung mass is a good thing
This is why I was surprised when you said it was better with the 16" wheels…
What’s better to me may not be to someone else, it comes down to preference. The 1.5 has less power, a bit less weight and much more character in the engine in that you can use more of it more of the time in the real world, my opinion.
On the subject of the thread, I’ve bought wheels before because they look better rather than they will improve the handling (sure I’m not the only one…), go with what makes you happy.
Nope, I meant 25mm
If you left it at 45mm and made the wheel an inch wider it could go to far into the wheel well and then interfere with suspension components
This is why the likes of WillTheyFit.com are great, you can compare specs of different wheel and tyre combinations:
Orange are the 17" ND specs from Mazda
Green are the specs I suggested with 25mm offset
By reducing the offset you are pushing the face of the wheel further out from the hub
Notice how the back sides (right) of the different specs are almost inline but the faces (left) are considerably different
This would fill out the wheel well considerable without interfering with any suspension components and remove any requirement for spacers
On my ND I run 25mm spacers all-round this brings the face of the wheels to just flush with the body
However I do have some rubbing on the front right plastics due to the large spacer and lowering springs I also have, most go for 15mm or 20mm spacers instead
the offset is measured from the middle of the wheel to the mounting flange. if you use a 7", 7.5" or 8" width you would want to keep the tyre in the same position - you will be using a wider tyre but the centreline is the same - so offset is identical to stock (if you can find a wheel with the same offset)
For the NC 200 - 225mm tyre width should be fine with the stock offset (or near enough). If you go wider then you would have to start thinking about moving the tyre & offset the centreline using different wheel offset as you suggested as well as fender rolling. As I said, I have no idea what would fit the ND
Correct, it depends what you want to accomplish
I have already moved the tyre by fitting spacers to my car
Therefore, if I was getting new wheels I would be going for specs like that so I don’t have to run spacers
Then I get the aesthetics I want as well as the additional width
But, yes, you can probably get away with running a 8" wide wheel with the standard 45mm offset
You are adding 1cm or so to the back of the wheel in the wheel well so I would still check clearances
I’m on 17 x 8j et45 and they fit perfectly without rubbing issues, even on Eibach springs (215 45 17 tyres). They’re still lightweight too, which to me was very important to keep the nimble steering/handling feel. These will fit big brakes without the need for spacers as well (I’m selling some 6 pot wilwoods in this same colour if wanted)
Not so I’m afraid, a smaller diameter wheel is usually lighter. Manufacturers make it so they both have the same overall diameter (or the speedo would be out) but the smaller wheel has a taller tyre. You either have more rubber or more metal to make up the diameter. It’s not just the extra weight of an inch of metal spokes, but the extra circumference of metal rim that makes the difference. In short more metal is heavier than more rubber.
The factory ND 17" wheel weighs 17.8 lb
The factory ND 16" wheel weighs 14.3 lb
and here’s the tyre weights (Kumho 51):
So a 16" ND wheel & tyre weighs 32.3lb
17" ND wheel & tyre weighs 37.8lb
That’s quite a difference in unsprung weight that you’d definitely notice the 16’s being livelier.
Completely agree you would want to reduce the unsprung mass, I accept that the wheels maybe becoming heavier however the delta between the overall weight of the wheel + tyre is not that simple.
I’m referencing the tyre weights from: Kumho Ecsta PA51 Tires
you chose the 195/50/R16 and compared it with the 205/45/R17 however the two tyres are not only fitting on different wheels but also have different width. So if you were to compare a 205/50/R16 with a 205/40/R17 - that I would chose to have an effective diameter more similar to stock - the 205/40/R17 is lighter.
195/50/R16 - theoretical diameter = 601.4 mm , weight = 18 lbs
205/50/R16 - theoretical diameter = 611.4 mm , weight = 20.1 lbs
205/45/R17 - theoretical diameter = 616.3 mm , weight = 20.1 lbs
205/40/R17 - theoretical diameter = 595.8 mm , weight = 18.8 lbs
However as you said between the 195/50/R16 and the 205/40/R17 and considering that the 17" stock wheel is 3.5 lbs heavier, if you were to go for this solution, the unsprung weight would increase. A mitigation to this would be to look for lighter wheels.
However regarding tyres - if you look at two tyres with the same tyre tyre width and the same overall external diameter the one that fits the bigger wheel it has to be lighter.
I love these wheel/tyre debates, there’s no real right or wrong answer because as soon as you see a new wheel we like the style of, all logic goes out of the window! 
I chose those 195/50/16 and 205/45/17 tyre sizes as they are (I think) the tyres that Mazda fit to a 16 and 17" ND wheel which the 16" one the OP has.
Very true, but how many of us can resist going a little wider on that oh-so gorgeous shiny new wheel 
Not many mate (and I’m including myself 
)
Some 17 inch Konig’s or Enkei’s look mint 
I have a set of 17’’ alloys (not sure of make), with almost new Firestone tyres for sale, cheap, if you want to try them?
