I read a bunch of threads saying it won't clear, doesn't fit etc.
I've test fitted a set of 15" *6.5" Racing heart CP035's from the ITR and they clear the rear no issue. They also clear my Rotora 4 piston mini front caliper and stock caliper if spaced out.
I'm confident a 15*10" +38 with high disk face will clear without issue.

The whole reason I'm looking at this is I'm running out of travel with the 285 30 18's I'm test fitting. The lowest I can get the car while still having adequate suspension travel is 3.75" ground clearance. I'm confident getting the ride height down to 2.5" will improve handling and aero substantially. With the 18's it would mean cutting out a good portion of the front upper frame member, and running with the rims well up in the fenders, and substantial rework of all the suspension mounting points.

The 275 35 15 A6 and R6 that Hoosier offers is 23" in overall diameter versus the 24.9" of the 285 30 18. This puts the car at 2.75" ground clearance as it sits, and with another 1" of room for compression travel, can reach the 2.5" target without issue.

Plus, it should be substantially lighter, and it does fit. The 15 does look tiny, but at the end of the day if it's quicker, I think it could be a good way to go.
Working on picking the right rim now.

Andrew

 

interesting... I'm curious of the tire weight differences between 18" and 15". going to investivate that now.

 

hoosier a6 in 275/35/18 is 23lbs per tire.
hoosier a6 in 275/35/15 is 20lbs per tire.
r6 is same weight.

CCW website shows a 18x13 rated at 24.3lbs. I would guess 18x10 being 21.x. How heavy are 15x10" rims? under 15lbs maybe?

huge weight savings, this is very interesting...

 

damn I'd always wanted to run 15's, you 100% sure they clear the stock brakes?

you can get 12lbs wheels and a great tire selection because all the spec miatas run 15's

 

the miata stuff is 4 bolt unfortunately.
The front rim has to position the larger diameter portion of the barrel over the caliper, but with the 15*10 +38 fitment I'm planning to use this should work out no problem.

The 6.5" Racing Hearts fit the rear without spacer. They fit the OE fronts with 20mm spacer, and the Rotora 4 piston with 35mm spacer.

 

What a setup to have................lots of work to do to achieve this though. Kudos to those who do.

 

and in the end, Miata's will still be able to outcorner us

 

intresting. if you get this to work id love to see some pics of it done ill be intrested to here your feed back

 

also considering the Dunlop slick 260/605R16.
It's a full 1" shorter than the 285 30 18, but apparently a faster tire than the Hoosier R6.
There isn't much information available on the Dunlops but we've seen some impressive results here.

 

Hehe, that's pretty funny! I was thinking of ways to run 15" wheels also. The only problem for me would be the tires wouldn't be legal for "Street" Class....if I opted for the 10-11" widths. I wanted to minimize weight, yet have a little meatier tire for with a good contact patch... I admit that I never really concidered to increase suspension travel in my set-up with those wheels, but I was planning on lowering my front lip/splitter and sideskirts for aero purposes while maintaining a slightly lowered ride height, instead.

Now, if only someone made 15" DOT approved tires that came in my prefered width...

I look forward to hearing more about the progress of your Unlimited build down the road! Best of luck to you, Andrew.