The Mazda Miata is incredibly sensitive to what is called 'unsprung weight' (which can best be understood as what hangs off the Miata suspension rather than what sits on it). I was surprised when I bought my first Miata in the early 90s when I ended up not enjoying the very first set of very nice wheels I picked because the ride quality became poor. Most Miata owners can feel a deterioration of ride quality from a gain of as little as 2 to 3 pounds per corner in unsprung weight. We therefore strongly recommend that you use only light weight wheels for your Miata like those we sell here. Unlike other vendors who rely on overly optimistic wheel weights as listed by the wheel manufacturers, we weigh each wheel that we sell to verify the lightness. For that reason, many of our listed weights here are slightly higher than the marketing weight listed on the wheel manufacturers' websites.
Miata wheel offset causes a lot of confusion. Here is a simple explanation. If the rim is 6 inches wide, and the mounting surface of that rim (backside of the bolt holes), is 3 inches from either outside tire bead surface, that rim has a 0 offset. To the extent that a rim's mounting plane is offset from that zero position, that offset is measured in millimeters. For the 1990-2005 Mazda Miata the factory offsets are 45mm for 14 inch wheels and 40mm for factory 15s, 16s, and 17s. Lowering the offset number from 45 to 40 to 35 is moving the wheel further outboard. Stick to the range of 38-45mm for stock height to avoid concerns with fender lip rub. Those with lowered suspensions and 1.5 negative camber or better can pick a more aggressive offsets like 35-38mm and still clear factory fender lips easily with 195/50/15 or 205/50/15 tires. Offsets lower than 35mm will often require fender lip roll, particularly on the NA generation Miata (1990-1997). Those looking to have the wheels flush with the rolled fender lips will often pick even more aggressive 20mm to 30mm choices. Spec Miata racers are usually using 25mm offsets. We have numerous 15x9 choices for those racing with 225/45/15 and these wheels require changing stock suspension for more narrow coilovers (like our TEIN and Ohlins coilovers), in addition to fender lip rolling. Please contact us if you have any questions on appropriate offset for your intended use.
Note the Miata is VERY sensitive to wheel balance issues and many shops do not have equipment that can balance the combination precise enough. Therefore, we suggest finding a shop near you with a Hunter Road Force Balancer (Just google Hunter GSP9700 and enter your zip code in their locator). Torque lugs to 85 ft/lbs and check that torque again every week for first month of owning new wheels or lugs. We ended tire service, the Miata is just uniquely too sensitive to wheel balance issues and we came to realize Customers are best served by getting tires local with a lifetime mount and balance deal that most shops either include or have as an option these days. We can send perfectly balanced sets, 'road force balanced' which is what the Miata needs, but over time with wear you need another re-balance often with the Miata and sometimes just a little rock bouncing up from the road knocks off the balance weight and you need that re-balance yet again to avoid the dreaded Miata 'shimmy' at 60mph. If the Miata was not a convertible it would be a lot stiffer, a lot less prone to this issue, but we all love it because it's a convertible so consider getting tires local and re-balanced as needed yearly as worth it for the fun factor. Note our site will let you ship wheels direct to your top local tire dealer if you like.
Most modern wheels are clear coated just like the paint on your car. Therefore, do NOT use anything on your wheels that you would not use on your Miata. Only clear coat safe products should be used on wheels. We like to put a coat of fresh car wax on new wheels before we put them on our Miatas here, helps keep them clean.
Hubcentric rings ensure that the wheel is centered on the hub, even before the lug nuts are tightened down. It's a nice bit of low-cost piece of mind knowing that you can't end up with a wheel off-center due to incorrect lug nut tightening. However, hubcentric rings are NOT mandatory. The lug nuts seats are conical for a reason; as long as you tighten the lugs correctly (done by hand and in a criss-cross pattern) then the wheels self-center as the lugs are tightened. However, some shops don't take the time to correctly tighten lugs, they just zap them on with an impact gun and the Miata is too sensitive to imbalances for that to be good enough. So, you don't have to use them, but they won't hurt and they're cheap insurance. As a rule of thumb, the racers know they don't want hubcentric rings because they know what they're doing and the rings just become an extra thing to worry about... but if you're asking if you should get hubcentric rings, then the answer is probably "yes" for you. Note that all our hubcentric rings are sold as sets of four, so order just quantity one for a set of wheels.
Torque lugs to 85 ft/lbs and check that torque again every week for first month of owning new wheels or lugs.