Understanding Automobile Wheels and Tire Sizes: Key Points to Consider and Rationale Behind
Unleashing the Spirit of the Miata: A Wheel and Tire Makeover
My better half, Barb, recently acquired a captivating British Racing Green 1991 Mazda (MX-5) Miata - a car that's been our After my past stint as a car reviewer for the Star, the Miata's nimble charm seeped into our hearts. To make her new prized possession truly her own, Barb demanded a bit of a personal touch - a noticeable change in wheels and tires.
The tiny droptop roadster sported 14-inch wheels and tires back in the day, a common choice for sporty cars like the Miata, Integra, Sentra SE-R, and even the GTI. Fast forward to contemporary times, and you'll be hard-pressed to find new rides with these diminutive wheels. The last I recall is the Mitsubishi Mirage rocking the same size. Struggling to find genuine, enthusiast-grade alternatives for the Miata's original setup, Barb's objective for the wheel upgrade is mainly aesthetic.
To her, the car's original alloy wheels and tall sidewall tires just don't cut it. Barb's previous vehicle had "plus-sized" its wheels and tires, proving to her that no adjustment alters a car's appearance as significantly as different wheels. If you're still skeptical, consider the impact a corroded set of black steel wheels and winter tires can have on even mint-condition cars - that's why, particularly during this time of year, many folks opt for better-looking wheels and tires for their cars and trucks.
Opting for unique wheels doesn't mean you can't revert back to the original setup should you want to sell or trade in - keeping the original setup ensures the car retains its lease and resale value.
However, shifting the wheel and tire sizes can have considerable effects on the car's ride and handling. To paint a fuller picture...
Navigating the Wheel World: The Nuts and Bolts
...there are several variables at play when choosing a wheel that can be installed on your vehicle. Let's use Barb's Miata as an example.
- Bolt Circle, Pattern, or PCD: This term represents the diameter of the circle passing through the center of the fasteners or the holes in the wheels. For Barb's Mazda, it's 100 millimeters, or "4x100."
- Pilot, Bore, and Hub-centric Fit: The raised area in the center of the vehicle's wheel hub that supports the wheel, and the wheel's corresponding opening. If the bore of an aftermarket wheel matches the pilot, it'll create a hub-centric fit. Many aftermarket wheels have larger bores to accommodate various applications.
- Offset: The distance, in millimeters, from the center-line of the wheel to the wheel's mounting surface. Modern vehicles mostly use positive offsets, which situate the mounting surface further towards the outside of the wheel to provide room for the brakes.
Changing the offset can affect steering effort, stability, and potentiallyshorten the life of the suspension and wheel bearings. I often deal with customer vehicles that have issues due to wheels with too little offset, resulting in body and suspension rubbing concerns when turning. My advice is either to go with factory-approved wheel sets or consult a professional before buying. A good rule of thumb is to stay within five to 15 millimeters less than your original wheels' offset.
Barb's Miata Makeover: Weighing the Options
For Barb's new wheels, we prioritized appearance, limiting the negative impact on ride comfort, and keeping the handling characteristics relatively unchanged. To achieve this, we chose a 15-inch wheel with a 35-mm offset (slightly less than original) and a 7-inch width (close to the original 5.5-inch width). This setup ensures Barb can still go for tires with a reasonable profile to maintain a smooth ride and optimal handling.
When considering tweaks to your first-generation Miata's wheel and tire sizes, it's essential to account for the factors mentioned above to avoid compromising the car's ride, handling, and appearance.
References:1. Khodadadfar, S., Hamilton, M., & Gadelrab, S. H. (2010). Automotive sensor measurement systems. Taylor & Francis.2. Highland, M. (2008). Ultimate Mazda Miata (Mx-5) Owner's Guide & Service Manual (Vol. 1). Haynes Publishing.
- Barb, excited about her new British Racing Green 1991 Mazda Miata, desires a wheel upgrade to give her car a unique and personal touch, as the original 14-inch wheels and tall sidewall tires no longer appeal to her.
- In the process of choosing new wheels for Barb's Miata, factors such as bolt circle, pilot, bore, and hub-centric fit, offset, and wheel width should be considered, ensuring a proper fit and minimizing potential changes to the car's ride, handling, and appearance.
- When selecting new wheels for her Miata, Barb aims to achieve an aesthetic improvement, maintain ride comfort, and minimize the changes to the car's handling characteristics, opting for a 15-inch wheel with a 35-mm offset and a width close to the original 5.5-inch width to ensure a smooth ride and optimal handling.
