Help sourcing 15" steel wheels for a big brake SVT

Technical Area Wheels, Tyres & Brakes
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  1. My model of MX-5 is: 2002 NBFL Big Brake SVT
  2. I’m based near: __Bristol
  3. I’m looking for technical help or recommendations on: __15 inch steel wheels

Last summer I did a John o’Groats to Lands End run in my 02 SVT Madge and ever since completing it the ridiculous notion of a round the world run in Madge has been growing on me at an alarming rate.

When this might be practicable with the current global health issue is questionable, I shall be retiring in 5 years so hopefully by then the dreaded C word will be under sufficient control to permit leisurely overland travel.

I am sure I could chance it in Madge without any mods, however the idea of getting stuck some where with an unreadable, let alone pronouncable name, half way between Moscow and Vladivostock or somewhere high in the Andes with a 205 45 R16 puncture and a severe language impediment has made me consider what I can do to mitigate such a totally predictable misfortune.

My first thought is to ditch the space saver in favour of a set of tyre levers and make up the weight saved with spare inner tubes.

However inner tubes do not appear to come in a compatible size, so my next thought was to go down to 15 inch wheels with higher profile tyres, these might just be a little easier to source in Tierra del Fuego should I run out of inner tubes.

The wheel size.com website tells me I am looking for 15" wheels with a 54.1 mm centre bore, 4x100 PCD for the standard SVT hub.

Furthermore the tyre size.com website tells me that by selecting a 15 x 5-6" wheel size in conjunction with a 175 / 60 / R15 tyre I will have exactly the same circumferance tyre as the standard SVT set up which means my speedo will read exactly as it already does which could be handy for navigation if I need to resort to paper maps and related hardware.

So my first question is does the 15 x 5-6" wheel size mean I can use either 5" or 6" width with the same 175 / 60 / R15 tyre and keep the same overall circumference or have I mis interpreted what the 15 x 5-6" wheel size means ?

My second question is does anybody know what offset would be needed for a 15" x 5-6" steel wheel to clear the brake lines on a big brake SVT.

And finally does anybody know of any existing Mazda model or any other manufacturer of a 15 x 5-6" steel wheel with a 54.1mm centre bore and a 4 x 100 pcd ?

I’d like to avoid using spacers and spigot rings and will try and get wheels made up if none are available off the shelf.

Thanks in anticipation.

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As that’s a narrower wheel than standard, I’d be amazed if you need to consider clearance for the brake lines as they’ll intrude less into your wheel well than the OEM jobs, not more.

It’s an impressive mission, you’re lining up. I wish you every success! As the military has it, though:
“Prior planning and preparation prevents p*ss poor performance!” :grinning_face_with_smiling_eyes:

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Thanks Jitsuka, you are probably right about clearing the brake lines, but as the military know assumptions are the mothers of all SNAFU outcomes :wink:

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Back in the 1970s we did a complete overhaul on a 3.8 Coombes modified Mk2 Jag, triple SUs, gas-flowed special head (D-Type?), bigger brakes, 40gallon LeMans filler extra tank, etc.

We took it around the block, two miles, just to make sure all was OK before his big trip down to Italy.

Parked up again we noticed a drip of brake fluid from the front left, and it seemed like one of the new hard lines between the pistons had somehow moved and was now rubbing through. But how?

However, comparing it with the old rusty line there was about a quarter of an inch difference on where the bends were, nothing really, but the wheel bearing was not quite as tight as it should have been and that tiny, tiny bit of float was all that was needed to occasionally touch.

New lines all over again to the original shape, and new bearings on both fronts. That car was then good for several years.

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