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I've noticed that many of the miata's in the US run 225/45/15 tyres, but I've never seen tyres in this size in Australia?

Is anyone on here running this size and/or know of tyres available in this size?

I'm assuming you're referring to motorsport tyres.

Hankook R-S3, but not available in Aus yet as far as I know; see here: viewtopic.php?f=18&t=42910&start=30. Only takes 7 to 10 days to arrive from the Tire Rack in USA.

Your other alternative is the Kumho V70a http://www.fsport.com.au/kumho_tyre_sizes.html.

There could be others, but I can't think of them off the top of my head.

I've been down this route too, so here's what I found:

Kumho V70A 225/45/15s are the only ones you'l find in Australia but they're EXPEN$IVE at $380 per tyre:
http://www.mx5centre.com.au/index.php?main_page=index&cPath=80_92_93

That's WAYYY too much so I sourced mine from OS. Initially I wanted RS-3s from tirerack.com but there were none available and they didn't know when they'd become available (Hankook only make these in batches and they tend to get snapped up pretty quick). In the end, I shopped around the US for some alternatives and found some Toyo R1R 225/45/15s for US$20 per tire more expensive than the RS-3s and bought them - supposedly they're better in the wet than the RS-3s. These are still a soft wearing tyre but I saved over $350 by purchasing from the US, even after S&H.

The sensible buyer would settle for 205/50/15s at ~$179 per tyre (Kuhmo Ku36s or Toyo R1Rs).

MINX tried some 225/50/15s bought here but they rubbed in the front - it may not be an issue if you're not lowered too much up front though (or don't drive like MINX ).

I currently have 195/50/15's and next I was probably going to try the R1R or KU36's in 205/50/15.

Given the rarity and cost of 225/45/15's I think I'll give them a miss but it's an interesting size.

Hoosier also make a 225/45/15. They also have a utqg rating of 40 but are more expencive than the Hankook.
Does anybody know how these compare to locally available tyres?

Has there been any increase in the availability of this size since my original post?

Nitto NT01 comes in 225-45-15. Yokohama A050 also comes in 225 but they are a bit taller, 225-50-15.

I'll bite, why do you want to run 225/45/15? A wider tyre does not mean more grip...

A wider tyre has a wider shorter contact patch while a narrow tyre has a narrower longer contact patch. The contact patch area depends on the tyre pressure, the deformation of the sidewalls and other 'stuff'. A wider tyre has a larger contact patch only if the tyre pressure is lower than in the narrower tyre.

When cornering the contact patch is being twisted, or the tyres slip angle. The wider shorter contact patch on a wide tyre has a smaller slip angle and as a result grips better PROVIDED it is up to its optimun temperature. However, a wider tyre does have better heat management abilities than a narrower one. Hence a wider tyre can be of a softer compound.

Do a search on Pacejka if you want to know more...

Why? Car is a mostly track dríven car with considerable straight line traction breaking power, tyres are always up in temperature in this environment. I would adjust my tyre pressures to suit. Also I've been running 205/50-15's for years and I've noticed a lot of the fast turbo guys running 225/45/15's but they seem to import them privately. It's a case of I'll try it if they're easily available and see how I go.

I understand the contact patch considerations especially in relation to 4wd's, however if wider was no advantage why would anyone upgrade from 185/60/14's? The tyres are certainly cheaper!

My bad. Out of interest what tyres do you run and what are their temps, I assume you are running a pyrometer?

I have a set of 225/45/15 Kumho V70A for sale if interested? Brand new and were heat cycled before I bought them

I saw a set of rs3's in that size on eBay for $648.
They were from jdmyard.
Obviously imported and not Australian delivered but a good price nevertheless.

Ebay
Hankook RS3 225 45 15 AU $648.00 +AU $80.00 postage
2 X New 225-45-15 NITTO NT01 SEMI SLICK RACE TYRES ! AU $400.00
HANKOOK RACING SLICKS VENTUS Z214 Tyres 225/45ZR-15 AU $295.00

Magpie wrote:I'll bite, why do you want to run 225/45/15? A wider tyre does not mean more grip...

While on this subject....
225 is the recommended width (by manufacturers & including r specs) for 8" rims, & the maximum recommended rim for 205's is 7.5"
However I see a lot on this forum running 205's on 8" rims? - any problems? quicker lap times (with r specs)?

Cheers

Currently running KU36's 205/50-15 which aren't as good as the R888's I've used previously. Cost is the factor unfortunately. I'll probably get R specs in 205/50-15 again in the future as I'd need to invest in wider rims to get the full advantage of the rubber.