Upgrading tires and wheels is a popular way to personalize one’s vehicle.
With a passenger car, it’s best to maintain the original tire diameter, so the plus-sizing method is used. In this case a larger diameter rim is matched with a wider, lower profile tire.
The larger diameter wheel looks good and the shorter tire improves responsiveness and lateral stability. Maintaining the original overall diameter maintains speedometer/ odometer accuracy, doesn’t compromise brake system operation, and minimizes the chance of accidental fender contact.
Plus sizing may also be done on trucks when a lower, street performance look is desired. One should note that shorter tires typically have reduced load capacity, so a truck with 20-inch rims and rubber band-thin tires is not a good choice to bring home a yard of pea gravel from the garden center.
If a brawny, off-road capable look is desired, one typically chooses a larger tire size (maintaining a similar tire height/width ratio) with the same or larger rim diameter.
The larger overall size increases load capacity and vehicle ground clearance, provides better flotation in sand or mud, and may contribute to longer tire life. The down side is braking performance will be slightly reduced, the speedometer/ odometer will be affected, and front fender clearance issues may arise.
Larger tire diameter may slightly increase fuel economy, but increased width typically cancels the gain.
Go to www.tirerack.com and look up replacements for your stock tires, then choose “specs.” You’ll find tire diameter, width, load capacity, wheel width range, and revolutions per mile. You can then look at larger tires in that same brand/tread style, and note the critical dimensions.
Prior to actually buying tires or wheels, consult a knowledgeable tire pro at the supplier you choose, asking them to verify correct fitment.
Finally, the speedometer/ odometer: Going up two sizes (245 to 265) would cause about a 4 percent error (you’ll be driving faster than indicated). Correction is possible. Depending on the truck, this may be a simple scan-tool procedure or more trouble than it’s worth.
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