Plus Sizing For Style And Performance
Plus Sizing means different things in the world of fashion and the world of tires
. In fashion it means designing stylish evening apparel, daywear and lingerie for women in sizes ranging from 14 to 32. Among auto enthusiasts it means enhancing the appearance and performance of a vehicle by installing lower profile tires on wider and larger diameter rims.The Plus Concept
The Plus concept was born when performance-minded owners and tuners began putting wider tires and larger wheels on their cars, trucks and SUVs. But, one problem they needed to overcome was speedometer accuracy.
Speedometers are precisely calibrated to the rolling diameter of the tires. At 55 mph a 15-inch tire rotates 817 times per mile and, after one hour, the odometer records 55 miles travelled. A 16-inch tire rotates only 785 times per mile. If 16-inch tires are used on a vehicle with a speedometer calibrated for 15-inch tires, after one hour the odometer will record only 52 miles travelled. In this example, the difference in both the speedometer and odometer reading will be about 5.5-percent.
However, performance-minded owners soon discovered that if wheel diameter was increased (from 15-inches to 16-inches) the same rolling diameter and speedometer accuracy could be maintained by lowering the aspect ratio of the tire.
Aspect ratio, often called tire profile, is the ratio between the tire's section width and section height. It's expressed as a percentage (70, 60, 55, 50, 40) and appears as the second number in the sidewall lettering. The higher the number, the taller the sidewall. The lower the number, the lower the sidewall.
Plus Benefits
In theory, a 205/60R16 tire has the same rolling diameter as a 225/50R17 tire. The larger 17-inch wheel can significantly change the appearance of the vehicle. Substantial weight savings are also possible by switching to a larger, more stylish yet lighter weight wheel. In addition, the wider and lower profile 225/50R17 tire enhances traction and cornering performance, and also contributes to quicker steering response. And, all those benefits can be gained without sacrificing speedometer or odometer accuracy.
Plus Numbers
If you're interested in Plus Sizing, most tire stores offer affordable Tire and Wheel Packages as well as knowledgeable sales consultants to help guide you through the process. You could Plus Zero, Plus One or Plus Two. The number following the Plus denotes the number of inches added to the diameter of the rim. A Plus Zero is a change to a wider tire, using the same diameter rim.
Plus Zero
Original Tire: 205/60R16
Plus Zero: 225/55R16
This example uses the same wheel diameter (16-inches) plus a tire wide a wider section width (225 mm) and lower aspect ratio or profile (55).
Plus One
Original Tire: 205/60R16
Plus Zero: 225/50R17
This example uses a one-inch larger diameter wheel (17-inches) plus a tire with a wider section width (225 mm) and much lower aspect ratio or profile (50).
Plus Two
Original Tire: 205/60R16
Plus Zero: 245/40R18
This example uses a two-inch larger diameter wheel (18-inches) plus a tire that with a much wider section width (245 mm) and a significantly lower aspect ratio or profile (40).
Look Before You Plus
The first step in Plus Sizing is to consult a qualified tire professional. It's best to avoid online or catalog sales, if possible. Most tire stores offer affordable Tire and Wheel Packages, so you can visualize the end result before you purchase. A qualified tire professional will also help ensure that your new tires match the load capacity and speed rating of your original equipment manufacturer (OEM) tires. Automotive Service Excellence (ASE) Certified technicians will also check clearances between body components under full suspension, maximum load capacity and severe steering conditions.
So, if you're interested in enhancing the appearance and performance of your vehicle go for the Plus. Stop by your local tire shop to see the many affordable Tire and Wheel packages they offer. A knowledgeable sales consultant will also guide you through your Plus Size adventure.
by: Wally Koster