I know there have been a few tyre questions lately so I hope nobody minds if I just throw another one in.

Just wondering what size tyre people with 16" rims are running. My TE came with some 16" alloy 5-spokers (which I don't really like) and looked pretty good. I can't remember what size tyre was on it back then, but when I put new tyres on (Turanza 215/60R16 - as suggested by the tyre place) the rims looked really small. Yuck, too much rubber.

Open for discussion...

i run 225/50/16 on the rear pic of my avatar

It said legally a Magna with 16's can't go to 17's as the OD of the tyre won't meet the tolerances of the local traffic authority.

Realistically, Magna owners get shafted unless you own a car which had 17's fitted by the factory.

That's not right.

Apart from the load rating problem on TE's (95 load rating needed) you can pretty well fit any diameter rim you want, as long as the OD of the tyre is within +/- 13mm of the original fitment on that car.

Now, my TH sports came with the 215/60 R16 tyres you mention. They have an OD of approximately 664mm (calculated using the following formula:)
OD = tyre width (mm) x aspect ratio/100 x 2 + Wheel diameter (mm)

So, for a 215/60 R16 tyre, the OD is:

(215 x 0.6 x 2) + (16x25.4) = 664.4mm

The 225/50R17 tyre I fitted instead has an OD of:
(225 x 0.5 x 2) + (17 x 25.4) = 656.8mm

Note that these calculations are approximate, as different manufacturers vary slightly in "claimed" and "actual" width and aspect ratio.

Of course, load and speed ratings are another matter, and they can cause a bucketload of headaches.

Cheers

Warps

Aspect ratio?

BTW, my Sports came with 16s and also has 215/60 16" tyres.

http://www.miata.net/garage/tirecalc.html

Any idea if these tolerances are the same across all the transport authorities?

Not sure about that one. I researched this very thoroughly when I bought my Magna in 1999, (was living in NSW at the time). Of course, things may have changed since then (I haven't kept right up to date, I must admit).

I can't guarantee that all the regulations are uniform across the nation, though. I know that a lot of vehicle regulations differ from state to state, but tyre regulations seem to have been pretty uniform from what I could gather. From what I've seen, the restriction on OD has been pretty uniform (although some authorities say it has to be within Xmm of the tyre originally fitted to that vehicle, and others say it has to be within Xmm of the any tyre available for that vehicle from the factory)

I do recall seeing something about only being allowed to go up one or 2 sizes in rim diameter, but I can't recall whether this was a transport department restriction, or an insurance company restriction (as the insurance companies have their own set of limitations)

From what I can gather (and I apologise to everyone interstate), NSW NRMA Insurance says there is no restriction on rim diameter, but you can not have rims more than 2 inches wider than the spec on the tyre placard. As to whether the RTA agrees with this, I'm yet to find out.

That's interesting. I nearly changed away from NRMA because they wouldn't let me go any wider than 1" over what was on the car originally (16 x 6 to 17 x 7). AAMI were going to let me go to 7.5", but hten they wouldn't let me lower the car at all (not that I've done that yet, after 4 years :oops: )

Not doubting you, it just seems to be another sign of the moving goalposts.

I spoke to the RTA Engineers about it at the time, and they said that they go by what the manufacturer says, and I recall Mitsubishi at that time said that up to 1" wider than standard is acceptable. That was why I stuck with 1".

Of course, this is all starting to split hairs. At the time, I was driving up to 80,000km a year, on all kinds of roads, and the last thing I wanted was hassle with insurance, or a wheel breaking off in the middle of nowhere (believe me, some of the aftermarket wheels I looked at were very dodgy in design)

Well I might send an email to the NRMA, the RTA and maybe Mitsu and get some straight answers from the horses mouth. Maybe the NRMA have different policies in different states.