You would just unbalance the car.
In the corners, perhaps. But I was thinking more about grip on the drag strip. There are a lot of cars with staggered fitment. My BMW has 225 in the front 255 in the rear.
A 1.6 old MX5 is a terrible choice for a drag racing car. Chop it in for an old Jag V8; they’re cheap at the moment
Going back to the original question 
It feels like the general input is that 15” doesn’t rub for most tyres and a sensible ET. What about with 8” wide as apposed to 7.5”.
Also does anyone know what inch is on th e V-spec ‘daisy’ wheels I have on it? Just wondering how much wider 8 would be .
I’m asking as the wheels I want are not only 15” but also 8 not 7 or 7.5”
Thanks in advance 
Sorry I just saw this after that post. Hmm seams like a lot of people are running 15” though with no run or rolling?
Why would they say that if it wasn’t the case?
Could your calcs be off maybe? You lost me with how you worked that out to be honest.
Based on your calcs - (8 x 25.4) / 2 - ET25 = 77.
So that’s outside of your range. What does 66 and 78 represent though? Seams like random numbers?
This link shows the standard wheel and tyres sizes for MX-5’s :- https://www.wheel-size.com/size/mazda/mx-5/
If you know what size wheels and tyres you have here is a calculator that helps give some idea if what you would like might work :- https://www.willtheyfit.com/
5.5"
15x8 is a little bit of a stretch for 195/50 15 tyres.
Wow really that small?
Seams very small if all the wheels advertise I’m looking at at 7 - 8
Regardless, of stress. I’m not fussed about that at this stage. I’m asking if the wheel will rub and to not roll.
I know a lot of people have given graphs etc but there are big gaps in between some specs.
So will a 15/8 inch. With the perfect tyre for an 8 in on it. Rub and I’ll need to roll. Or will I be ok. Or will going 15/7.5. Again with its ‘perfect’ tyre fit. Be a better bet. ?
Cheers
The wheel never rubs, unless its the inner part of the rim kissing 1.8 front calipers (possible with some banana spoke Minilite type wheels). Its always the tyre that will rub
15x8s with 205/50s will generally rub.
Generally, off set no less than 30mm, wheel size 15x7. Oh, have you considered centre bore size at all? Factory wheels are hub centric. And weight, because unsprung mass is important. Generally, keep to the factory issued wheels. If on a budget, the Mk2 15x6 wheels are very good; easily available and a very good weight.
My old 91 on Mk2 15s (15x6, 40mm offset)
These had replaced mag alloy 14x6 27mm offset Watanabes, which rubbed on the front inner wing liner for some reason (and the car handled better when on the Mazda wheel)
Incidently, the silver car was on 15x8 Lorbers, with 206/50 tyres. They caught a little.
My 96 with factory BBS (15x6, 45mm offset)
My 93 S-Limited when it came to me on 15x7 Work CR-01s, 35mm offset. A very heavy wheel.
I changed these for Maxilite 15x7, 30mm offset (5mm shim needed as I had 1.8 brakes)
On my 1993 M2-1002, it came from the factory on 15x6 Panasports, quite a heavy wheel
15 x 7 with hubcentric bore is a good choice as long as you get a light weight wheel. No mods needed if the offset is correct ( Unless your car has been lowered a lot )