- My model of MX-5 is: RF Sport 1.5
- I’m based near: Doncaster
- I’m looking for technical help or recommendations on: Wheel downsize
Hi everyone,
After months of looking I’ve finally seem to have found a decent enough RF and I’m getting very very excited to be back in an RF!
With this in mind I’m already eyeing up some mods. I’ve modified several cars before so have a decent idea of what I want to do, and one of my ‘go to’ mods is usually wheel downsizing - in this case I’ve been looking at 15 inch wheels.
I’ve done a lot of research but cant seem to find a definitive answer when it comes to wheel sizes that fit over the rear brake callipers in the ND - can anyone let me know if they have experience running 15 inch wheels on any ND please?
I have seen multiple 2 litre cars running 15s but I am told it isn’t quite as straight forward or clear cut as that…
I am looking to get 15s with as close to flush offset as possible WITHOUT modifying fenders/liners
Thank you everyone
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Here’s mine. Deliberately left with some ride height / wheel travel for b road blasting.
Wheels are RPF1s, 7x15, ET41, 18mm spacers front and 20mm rear. 185/60 tyres gives a bit of stretch, which I didn’t really want, but c’est la vie. The barrel of the wheel is veerryyy close to the calipers - it appears to be an RPF1 thing in this specific size. I know the 8" ET25s will clear even the larger brakes on the 2L cars! So it is pretty wheel specific.
If you Google search for ND5RC 15 wheel or something similar, you will get a few more results. ND5RC is the comminly used name for the car in Japan, and they tend to do this mod quite regularly.
The weight saving for me was brill, around 3.5kg a corner. Car is much more lively.
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Thanks Fabio! 
Lots of good results for Japanese cars.
Also check out Pure Roadster on YouTube:
https://youtube.com/@pureroadster59?si=vQHqXoS9fMtMyqnZ
Oh wow, thank you very much!! 
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I’ve got a question regarding fitting new wheels on the MX-5.
I’ve previously modified cars but they’ve always been VW group cars so when fitting new wheels with a smaller offset you always put a set of longer bolts to go with the new wheels. The MX-5 of course has lug nuts instead - how do you handle wheels with a smaller offset? Is there a special set of lug nuts or something…? 
Offset of actual wheels shouldn’t affect the stud length requirement as you are mounting the back face direct to the hub. Normally longer bolts or studs are required if using a spacer and whatever the spacer thickness is needs to be added to the length of the fastening.
Lower offsets are achieved through the wheel design having more poke as in the outer face extending further away from the hub
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Thank you very much for the reply - I’ve never used spacers and would rather not, so from what you’ve said would I be right in saying that I can buy wheels for the MX-5 with whatever offset I want (within reason!) and bolt straight up - I’m assuming aftermarket nuts would be needed? (something to do with conical seats and what not…?)
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Spacers are fine and I had them on my previous car for 5 years with no issues, but if you’re looking at aftermarket wheels better to get the best offset for your requirements to begin with and avoid if possible. A lot of aftermarket wheels (but not all) have a smaller pocket for the nut so will require tuner nuts which are normally available or supplied with wheel packages and will need to be the same thread pitch, size and seat taper.
Here are a pic of the ones on mine (but nc, aftermarket wheels either way) so you can see what I mean. These wheels are an inch wider than stock (8j) and offset 42mm and fit comfortably with a bigger tyre (215). Could of probably gone wider or lower offset but didn’t want any aggro.
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There are some great articles on Goodwin racing and bofi racing that detail what spec wheels fit each model mx5 and if you go on fitment industries they have comprehensive galleries of cars and wheels along with what brand/size/offset/suspension setup and whether it rubs at all etc…
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http://www.willtheyfit.com useful here.
Spacers are fine as long as you do it the “right” way (Google will explain it better than me!).
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Thank you very much for your input guys - and I’m clear on what you’ve all said, spacers are fine - if done correctly (I would just rather not) - I mean, if I’m going to be buying wheels I may as well get the offset that works, assuming it is possible! 
Thats how I’ve always bought wheels anyway
I also read up on what is safe and what isn’t safe to run offset wise on the ND platform so happy with where to look for when I’m ready to pull the trigger. The only thing I was really unclear on was the wheel nuts bit because I’ve never had aftermarket wheels on a car using wheel nuts - but sounds like it is very much the same as wheel bolts so my worries have been put at bay
Thank you very much once again guys, I really really appreciate it! 
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Agreed and also would rather have bought wheels with correct offset, but nobody seems to make them with all the other specs I wanted. So had to go to Plan B, which works out just fine.
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This is it, if can’t find the wanted specs thats when spacers work
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