mx5cartalk.com

Hey fellas,

I am interested in buying a set of wheels (15x7) from overseas but the pcd shows 4P. I'm assuming 4+ so would this be suitable for NA8 front & rear? The seller is telling me that offset is 104mm backspace. I can't be sure what that mean. Any help will be appreciated.

Cheers

PCD is "Pitch Circle Diameter" commonly stud pattern (ie: how many bolts, and the measurement of the centre diameter)
NA and NB were 4x100 (4 bolts, 100mm centre to centre)

Offset is the measurement of how far from the centre of the wheel the mounting face is. A positive offset means the mounting face is futher out from centre, meaning the wheel sits further into the car.

Backspace is a different way of measuring offset, it measures from the mounting hub to the back of the wheel.
It's a more useful measure to see if the wheel will hit suspension etc.



Thankfully you can calculate offset from backspace, and vice versa if you know the width of the wheel.

In this case your wheel is 15x7 so 7inches wide, this translates to 177.8mm wide.
If the backspace is 104mm we can do the following to work out offset.

104-(177.8/2) = 15.1mm offset (positive)

Backspace = offset + half width
Offset = backspace – half width


SO the offset on those wheels will be about +15
Bear in mind, wheel width is based from tyre bead mounts, not the external width of the wheel.
Often people measure backspace to the outer edge, so there can be a 10mm (roughly) margin of error there.

End result.
The wheels you’re looking at would have an offset of between +15 and +5 roughly.
I’d say +15 is more likely since that’s a much more common offset for that size than +5 is.



so yeah, lots of words, but now you should be all good for next time

If you want anything clarified just ask.

Mate, what a legend thank you. I needed to know this.

So would these wheels be suitable for the NA8C with bilstein and king spring (3cm lowered than stock)?

Cheers

standard offset is +45 on NA8's right?

standard rim NA8 rim is 6.5?
your new rim is 7" so then you have an extr 1/4 inch width which equals to 6.5mm ( little tiny bit less)
if the offset is 15 you would then have another 30mm exta with towards the fender
so overall your wheel will sit about 36.5mm further out than standard.

then it also depends on the tyre you use.

Ive only done this because I personally don't like agressive offsets & have never got into exactly what fits & what doesn't.
You may have to roll your guards. Not sure.

on the other hand there are lots of peeps with agressive offsets. They may be able to tell you straight out.

please check the facts as my mind has gone grey over time. I may have inadvertently given you wrong measurements as 6" some how sits in my mind as well for the NA8 as standard wheel size. you can check your wheel size on your door card

If your current wheels are 5.5 like on a NA6 just do the maths

NA6 daisys are 14x5.5 +45
Pretty sure NA8 are 14x6 +45ish
NB8A is 15x6 +40
NB8B is 16x6.5 +40?


As for fitting, I used to have 15x8+25 on my NB, and they only just fit without touching the guards (they lightly clipped the rear guard)

compared to an NA8 wheel they sat out 45.6mm further than stock.

your 15x7 will sit 42.9mm further out, which on my car would have been enough to clear, BUT, the NB has slightly wider hips than the NA.

Basically, it should fit, buy you may need to budget for having the guard lips rolled flat. (this is an invisible change if the person who rolls them knows what they're doing)

hks_kansei wrote:NA6 daisys are 14x5.5 +45
Pretty sure NA8 are 14x6 +45ish
NB8A is 15x6 +40
NB8B is 16x6.5 +40?

I'm sure my stock NA8C wheels are 15". My car is JDM import, would that be the reason? Except some interior and cosmetic parts, most parts are same as NB.

If I had to get the guard clipped or rolled, is there a recommended shop forum members use in Sydney?

I thought all the factory wheels for NA were 14s, but Japan had a lot more options available than the rest of the world, so perhaps 15s were one of them.

You can confirm the size by looking at the tyres, the tyre sizing will be something like 185/60R14
the last number is the wheel size in inches.

and yeah, NA8 shared a lot with the NB8A, main differences (non cosmetic) were the engine head, and a lot of aucilliary bits like exhausts etc.



I can't help with Sydney guard rolling unfortunately, but there would be plenty around.