Fitting 18inch rx8 alloys to an NC

Technical Area Wheels, Tyres & Brakes
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  1. My model of MX-5 is: __NC2
  2. I’m based near: __Grantham
  3. I’m looking for technical help or recommendations on: __fitting 18inch rx8 alloys to an NC

ive been toying with 2 ideas about wheels
one was putting 18inch alloys on and the other was spacers for my current 17s

however after some thought im not really keen on either for 1 reason on each idea.
first i simply dont trust the alloy spacers not to eventully break and secondly, this one is a bit more complicated.
basically i changed the wheels on my manta from the manta 14s to an after market 15 and they just didnt feell right!
i could feel that they were there unlike with the standard alloys so presumably they were the wring dish or incorrectly weighted for my car.
so when looking at 18s for the nc i kept coming back to are these weighted and dished correctly for the mx5

however a friend suggested looking at rx8 18in alloys as the nc and rx8 share the same platform presumably the rx8 alloys will be the correct weighted and dish etc

so i wondered if anyone had already done this and what the results were like?

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Mazda did an 18" wheel as an option, but one of the things they say you need to change is the clutch slave cylinder IIRC. (no idea why)

I tried these on mine , but sold them again and it is back on 17"

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Your wheels and tyres is part of the suspension.

The spring rate of the suspension system is primarily from the spring but it is also partially from the tyre.

Be prepared to fix bent wheels often.

You will be trading tyre material for aluminium and from previous discussion/calculations this will potentially increase unsprung mass which worsen the car handling behaviour

I prefer doing things that are driven by function not by looks. If you want to change something learn more about adjustable swing bars and how you can tune the car handling with them

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the biggest of my reasons for looking at different wheels is that i want the wheels to line up better with the edge of the archs without using a spacer!

lets be honest the standard nc wheels weather 16 or 17 have a kicked in look when viewed from the rear, which is why many people add wheel spacers!

iv just had a look at an rx8’s wheels and they do seem to come out farther than the mx5 wheels.

maybe the best fix would to see if there is a 17in rx8 wheel? as that way i would gain the width without trading rubber for alloy as you put it!

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did the 18s feel the same as the standard mx5 wheels or could you feel a difference?

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Have you tried this?

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RX-8 wheels are 8" wide and 50mm offset, which is why the stick out further. They are also bloody heavy.

Do you see lots of reports of wheels falling off cars with spacers?

If you want to fill the arches on 17" wheels you want a wider, lower offset wheel which is 17 x 7.5 with a 45 offset, to which you will fit 215 tyres.

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no I could feel the difference, that’s why it’s on 17" now

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You can put up to 225 tyres on your standard wheels. This would do what you want, I believe lots do it without much of a problem.

You have said you are planning to go supercharged so the increase in unsprung weight really won’t bother you unless you are competing in the car.

Mine has 215s on it and it has immediately made the arches look more filled. With the extra power planned you might appreciate the increased grip.

Best thing is to have a look and ride in a car with wider tyres.

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i was already planning to go to 215s if stay with my current wheels on my next tyre change!

however i have been considering swapping too the mx5 parts 7 and a half inch wheels and since making this thread i have firmed my decision that IF i do change wheels i will change to those.

so my next question is has anyone tried

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On a previous NC 2.0 I had 18” option alloys fitted, which looked great, but rode poorly in comparison to 17”. I personally prefer 215s on the 17” - I think they ride better.

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