Care & Maintenance — Technical
Plus One/Plus Two
The plus sizing concept was designed to enhance vehicle performance by allowing the fitment of lower aspect ratio tires than originally fitted to the car when new. Plus One/Plus Two retains the overall diameter of a vehicle's existing tire and wheel assembly by increasing the wheel diameter and reducing the aspect ratio (sidewall height).
By retaining the overall diameter of the tire, the revolutions per mile remain the same. Therefore, speedometer and odometer readings, gearing and engine computers are virtually unaffected. At the same time, the driver seeking dramatic performance improvements gains higher levels of cornering power, increased steering response and improved stability.
Today, automobile manufacturers offer Plus options on many new car models. One of the most frequent upgrades a car owner makes is fitting new wheels and tires. It is important that the plus sized replacement tire/wheel assembly retains the original overall diameter and that there is enough clearance in the wheel well to accommodate the plus sized replacement through the entire range of wheel/suspension travel and steering lock.
WARNING: Before you replace your tires, always consult the vehicle owner's manual and follow the vehicle manufacturer's replacement tire recommendations. Vehicle handling may be significantly affected by a change in tire size or type. When selecting tires that are different than the original equipment size, see a professional installer in order to make certain that proper clearance, load carrying capacity and inflation pressure is selected. Never exceed the maximum load capacity and inflation pressure listed on the sidewall of the tire. Always drive safely and obey all traffic laws. Avoid sudden, sharp turns or lane changes. Failure to follow this warning may result in loss of control of the vehicle, leading to an accident and serious injury or death.
Finally, the Tire Technician must ensure that the plus sized replacement tire carries a rated load capacity equal to or greater than the original equipment tire, and must use the proper inflation pressure. (Never exceed the maximum tire pressure shown on the sidewall.) Please refer to your vehicle's Owner's Manual. Your Dunlop dealer can discuss with you Plus sizes for your vehicle.
