mx5cartalk.com

18\" wheels - are there tyres to fit the mx5 nb8b 205/45r16 correctly?

if so what size?

or if not, is 17\" the biggest to go??

thanks in advance!!

205/45/R16 is standard size yes. You 'can' fit 18's but the question of why? no doubt will be asked.

thinking of fitting 18\" or 17\" to replace the 16\" wheels

but i cant find tyres to fit the rolling diameter. 17\" wheels use 205/40r17 which fits perfectly but there isn't one for 18\" wheels.

reasons for changing were
-change in 'shoes' for the car (different appearance)
-better handling (6.5 to 7.5 and lower profile tyres)

btw stock et is 40 will 17x7.5 et 42 fit the car?

I would query your better handling idea. Have a look at the size of wheels the guys that track there cars use. I bet you wont find an MX-5 track car with 18' rubber.

The disadvantages of having bigger rims, and subsequently wider and lower profile tyres are:

- bigger rims are much heavier (more unsprung weight), unless you go for superlight forged rims.
- bigger tyres are more expensive, especially with R-comp tyres
- harsher ride due to lower profile
- wider tyres subject more to aquaplaning. Wider front tyres will generate more resistance when they are steered.

The only thing going for lower profile tyres is:
- sharper steering response and better lateral stability due to stiffer sidewalls.
- Looks better visually

The best 18\" tyre that will match a MX5 is 215/35R18. That's 2.8% bigger in circumference than the 16's. Not sure how many good tyres are out there in this size, but I know Nangkang NS2 and Hankook ventus K014 are in those size.

I reckon you should stay with 16's or go with 17's at the most.

raplhie , as the others have said, bigger wheels will definately not make your mx5 handle better. if handling is a priority go for 14's or 15's. i had some 16's and they were good as well, but i wouldn't want to go any bigger than that. i'm running 15's now and i find them to be really good.

I've had no issues with handling with my 17's, as some people from the great ocean rd cruise can tell you. I think slugoid is right with the 215/35 tyres. Dino had 18's on his car and I believe this was the tyre size. People seem hung up on this wheel size issue. The only effect 17's have had on my car is that I get a crap load more grip. It would be interesting to see the difference on a track but in day to day driving I enjoy the extra grip around corners and to me they look bloody good. Go with what you want

Ben

bdscott wrote: The only effect 17's have had on my car is that I get a crap load more grip.

How does the wheel diameter effect grip?

Get decent light 15" rims (for less unsprung weight and better handling) and good sticky stiff sidewalled tyres (for more grip) if you want the ultimate performance package.

If you like the look of larger wheels and don't mind sacraficing some performance, go larger. Just remember, you can get really wide 15s if that is your reasoning for going larger, just look at green_comet's new 15x8s...

Boags

Boags'MX5 wrote:

bdscott wrote: The only effect 17's have had on my car is that I get a crap load more grip.

How does the wheel diameter effect grip?

Get decent light 15" rims (for less unsprung weight and better handling) and good sticky stiff sidewalled tyres (for more grip) if you want the ultimate performance package.

If you like the look of larger wheels and don't mind sacraficing some performance, go larger. Just remember, you can get really wide 15s if that is your reasoning for going larger, just look at green_comet's new 15x8s...

Boags

I understand that Boags and I am by no means saying that people are wrong. It is just that I believe too many people go on far too much about larger wheels being the devils tool. On a track I can understand the reasoning and as I said I would like to see the difference but on the road it is negligable. I am no slower than any other NA6 and do not suffer around corners more than any other Mx5 with similar suspension. I get a much harsher ride for sure but I like the look of them and feel that they fill the wheel arches better, but that is personal preference. The new Mx5 doesn't have 14's or 15's. The Lotus Elise doesn't have 14's or 15's and in fact off the top of my head I can't think of any modern day performance car that has smaller than 16's. They may not be everyones cup of tea but they are by no means worth mentioning the performance deficit everytime someone says they want to get 17's. Sorry it is getting late and I don't mean this to sound harsh but that is the way I see it.

Ben

No probs Ben,

My experience is that heavier rims make more difference on the road than on the track for me. It was parking, excellerating and twisty roads where I noticed the drag of the heavier wheels.

As you said, it's preference. If you like the look, go for it.

Boags

Each to their own I guess. But why stop at 18 inches, when you could have 20 inches?

http://forum.miata.net/vb/attachment.php?attachmentid=43037

http://forum.miata.net/vb/attachment.php?attachmentid=43038


J

i knew i shouldnt have opened those links thats horrible.

OT: 18's fit, but there is some scrubbing. i have 18's on mine and you may have them if you will. i want to get rid of them ASAP as they are a pain in the ass to drive with.

they do look good though but i'm after performance, not rice factor

pm me if your interested or look in the motorsport section for my build thread, photos are in there.

Has that thing had a front diff put under it too It already has the clearance of a 4wd

zoomzoom wrote:Has that thing had a front diff put under it too It already has the clearance of a 4wd

Funny enough most of the comments on the miata forum thread were along the same lines

J

ben i hear what you're saying, i agree people do go on about it a bit. but like i said, i found going from 16's down to 15's made a noticeable improvement in handling and feedback thru the steering wheel. that was my experience. but then again, even with 16's the car was a dream to drive. also, remember the original question was about 18's, not 17's. i just think 18's would be to big, as lil_mike can attest.