17s will compromise the cars rapid bump dampening tho. As would cheap coil overs. And wider rubber grips less in the wet and snow.
No, the overall mass of the wheel and tyre will affect suspension reaction and tyres will lose around 3kg over their life.
No offence to the OP but this comes over as classic Internet 'understanding" of what is needed and what is happening.
J6NGA
Don’t over think it. I assume you wanted coil over’s because you felt the existing set up too soft, even the ride height too high. To a great extent you do get what you pay for in suspension and so if you have a poor set up, wheels and sidewall height is not going to mask it. Assuming you wanted replacement suspension to improve sporty driving response, especially since you want “sticky” tyres, think of where you are coming from. To combat excessive roll, springs need to be stiffer. Damping then needs to be suited to the stiffer springs. Standard dampers are, by the nature of the volumes produced, very good quality for the price and will do what the manufacturer wanted from them. Replacements at the cheaper end of the scale are very unlikely to have the finesse of OEM product. However, the reason for the change in the first place is to get a firmer, more controlled drive. Unless you have spent a very large amount of money on your suspensions you are going to have to accept compromise.
Then, in addition, if you get tyres “sticky” that offer more lateral grip than “standard” tyres, you are going to be able to produce more lateral load and so more roll. If you want suspension and sticky tyres that assumes you want to go round corners faster, so don’t start worrying over sidewall height and the affect it has on ride. Yes, ultimately the tyre is an undamped spring and the internal damping frequency does have an effect on the suspension, but the likely hood of that being detectable is not even worth thinking about, particularly with after market suspension. Get light wheels and good road tyres and go drive.
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Not overthinking it is the most important part yes.
However the tyre IS a part of the suspension and the side walls are unquestionably the fastest acting part of the suspension.
When I bought my 08 NC in the autumn it came with new YOKOHAMA 205/50R16 87W tyres fitted all round. Lovely comfortable ride and excellent grip.
Some great comments on here, thanks, it is making me think.
I did indeed refer to coilovers. The main reason is lowering of the car, as the standard to me looks way too high. I could go for springs at £130 and reduce the height. BUT it was suggested to me the shocks may not be suitable being OEM and it would be counter productive.
Hence my thought of coilovers and Tein and Meister I have thought about and fixed Meister I think I am leaning towards (quality at a reasonable cost and I wont be tracking the car so no need to change the stance once done). This will stiffen the ride and allow better cornering. But in order to allow better cornering I feel I need better tyres. Currently I have some cheap poor tyres on there. I suspect the garage put them on to make it road legal at cheap cost.
So if the coilovers will stiffen the ride it will make it bump with more of a thud. So my thinking is not to go for 17s and lower profile tyre as it will exacerbate this thud. Keeping 16s with sticky good quality rubber is my thought and it will be more cost effective getting the wheels refurbed at £200 rather than a full new set at £400-£500 from somewhere.
Does what I say make sense or am I talking rubbish? I think my line of thinking is correct, but stand to be corrected.
The overall damping that the tyre contributes in the suspension assembly is very small. If you think of it as more of a vibration damping component. In general a 205 50 16 will be quieter and may reduce transmission of small high frequency bumps over a 205 45 17 but overall ride quality is provided by the dampers.
If you have a good quality fixed mono tube with correctly specified lowering springs (30 - 45mm) it will give you the improvements in look and geometry without compromising your priority for ride quality. Cheaper adjustable coilovers do not usually offer the same level of damping control as some of your money goes to the adjustable features of the unit.
You could consider https://www.mx5parts.co.uk/koni-strt-lowering-mk3-35-p-4166.html
You will still generate more grip from a 17x7 " wheel and have access to a greater range of performance tyres that appear to be much cheaper than the same make / compound 16".
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Long reply and lots of generalities.
Manufactures spend lots of effort tuning suspension and spring rates to what they want, or expect people to want, from a car. So the standard Mazda ride height, springs and dampers are designed to work together. There was lots of talk about the ride height when the MK3 was first released, but that is a different issue. What this means however, and I will use some made up numbers, is that the front springs will have a rate of say 250lb/in and the springs and dampers are designed to perform all the functions that suspension does within the suspension travel. Long travel soft, well damped suspension is great for a smooth ride, but runs in to problems when it comes to sports cars when you don’t want extreme cornering angles and also rapid changes in direction can result in some unwanted body inertia moments. When you lower the car, shorted springs, then the suspension travel is reduced, or certainly the part you are interested in, and so the cars needs to absorb bumps in a sorter distance and keep the car off the bump stops and so the spring rates need to increase. So now say the rates have gone to 300lb/in. This is what can lead to the common reported issues over ride issues. The standard dampers, tuned to 250lb springs are now being asked to deal with the same bump forces over a shorter distance and also control the rebound rate of the 300lb spring. This can lead to a poor ride and is one of the often reported outcomes of fitting lowering springs. Conversely, cars fitted with the uprated Bilstein dampers are often sited as being jiggly and crashy cope far better when fitting higher rate lowering springs because they were designed to deal with higher spring rates in the first place. These situations are what often comes up on the internet and gives rise to many of the stories about how one wheel size is better than the other etc. While a lower ride will be firmer, if the suspension is good, then there is no reason for it to be harsh.
Now it comes to wheels and tyres. It is very correct to say that the tyre is a compressive part of the suspension and being the part that contacts the road it reacts first to input. Getting technical it is an undamped part of the suspension but how much that affects the car between a 205 50 16 and 205 45 17 is down to many things. Tyre construction, air pressure, tread pattern and even wear rate. However, as above, the issues or not can be exaggerated by other factors including Dr Google and most you would be hard pressed to detect.
Starting with the made up figures, if your wheels were a tonne each, then both with just the physical mass and then the rotating mass, they have a lot of inertia and don’t want to change direction. As such tyres will mask things like road joints and effectively the wheel does not move and forces the tyre to absorb the imperfection. The problem comes however when the bump is big enough to to move the wheel. Now you have significant mass moving and the spring and damper needs to control that. More so, the heavier the wheel and tyre (unsprung mass) compared to the sprung mass, basically the rest of the car, then it means the car will move up and down more. Imagine holding a tennis ball in your hand. You can move it easily and quickly without it throwing you around. Change that tennis ball to a medicine ball, then not only are you going to have to use both hands and put a lot more effort in. You can’t move it as quickly and your body would move in reaction far, far more. What is more important than sidewall height is a wheel and tyre combination your suspension can cope with. Like for like, 17" wheels weigh more than 16". There are of course a number of 17" wheels that are lighter than the standard then the standard 16" wheels and far more choice in tyres. A light wheel combination will do more for your ride than sidewall. In addition that taller, more flexible sidewall will flex more with steering input and loads in corners. Also the standard 16" wheel is 6.5 width against the 17" 7" meaning the tyre is more “floppy” if you are after more direct feel. On the other side more tyre movement can make a more progressive drive as you approach the limit.
If you are concerned though, I would suggest that it is not “sticky tyres” you want but just not poor ones. If it helps your decision, Scott Mansell, who is Driver 61, uses a 2L MX-5 as a coaching car. That runs on 16" wheels and Kumho HS51 tyres.
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The suspension qualities m provided by the tyre is vastly underestimated. It’s of vital importance to mechanical grip. On a billiard table flat road they do nothing, but on bumps and lumps they act faster than any other suspension component. Even more so on light weight cars, hence F1 cars don’t use rubber bands as tyres.
I raced short circuits for years and something else you get from taller side walls is heat, they flex more and create more heat faster than lower profile rubber, after a 2.5 mile sprint 18s would reach 42 degrees and 17s 51 degrees. Same circuit and ambient temperatures. This heat helps your grip too. A heavier car would cause too much heat so you would add more air pressure. I don’t race anymore I instruct, so I don’t get to swap tyres and do these tests I just sit in whatever is provided.
I feel another testosterone war coming on. 
(It’s only meant to be a joke by the way…
).
it doesn’t have to be a war. People can have respectful disagreements. Even if I am right
Merry. Christmas you lot.
This is always the case with setups. There are many ways to skin a cat. Look at an F1 car, so many setups to achieve the same result. Always get disagreements on things like this. I expected lots of opinions which is why I asked the questions I have.
You also need to think about what you want. Ultimately you may not care about getting that last tiny bit of performance, after all it’s a road car and you want it to be usable. You will want it to be how you want it and if that means 90% as grippy then so be it. I used to be performance mad and spent stupid money on achieving the last little but I could squeak out of my cars. I went to fluid dynamic engineers to have engine and intake parts flow assessed and altered, I went to suspension experts to get my coil overs re-valved and set up for droop and sag… as well as ride height, when the drop and sag was set I wanted the car 40mm lower so I cut the suspension turrets out and welded them in 40mm higher so the dampers where in their optimum position, then had custom uprights made for the hubs with lower wishbone and steering connection points to keep the angles of them all within range and not enhance bumpsteer. I would spend any amount of money and not think twice.
These days, I like my car bone stock, I’ve tried a few mods and apart from the sound tube delete and auto window controller I’ve removed all of the mods and that’s how I like my car. Personal choice.
Basically I want it to be a road car to stick to the road and be comfortable in corners so that it will not spin out from behind me and come around but on open roads it is a smooth as possible.
It sounds like you need suspension refresh, reasonable new tyres and equally important a good 4 wheel alignment. That should tick all the boxes. Currently you have potentially poor or old tyres, shock/spring/bush ageing and unknown alignment.
100% correct MK375.
It’s like asking what kind of bread you should buy, everyone has their own opinion and it’s not yours.
Here’s mine, fit some Kumho Ecstas and drive it. 50 odd quid per tyre and you won’t find a much better all year round tyre.
Really you’re better off reading a proper tyre test and making your decision based on that V your price range.
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“…be comfortable in corners”
I’m no expert but possibly getting beefier anti-roll bars and reasonably good tyres will give you what you’re looking for at an affordable price.