Wheels and Tires
Reading the Sidewall
A size like P225/60R16 98H decodes as passenger tire, 225 mm section width, 60 aspect ratio, radial construction, 16-inch rim, 98 load index, and H speed rating. Replacement tires must meet or exceed the OE load index and speed rating. The DOT date code uses the last four digits (week and year) to show age; tires around six years old deserve scrutiny regardless of tread depth.
Wheels and Hardware
Offset is the distance from the wheel's mounting face to its centerline; positive offset moves the tire inboard and is common on FWD cars. Backspacing is measured from the inner edge to the mounting face, so the two numbers are not interchangeable. Match bolt pattern and hub bore - hub-centric wheels center on the hub, lug-centric wheels center on tapered nuts torqued in a star pattern.
Tire Service
Tread wear indicators appear at 2/32 inch; 4/32 is the practical wet-traction limit. Balance problems show as vibration at a specific speed; road force measurement catches stiff spots and runout that conventional balancing misses. Check radial and lateral runout on the wheel before condemning a tire. Directional and asymmetric tires must be mounted correctly.
TPMS
Direct systems use wheel sensors and require a relearn after rotation or sensor replacement, via scan tool or activation sequence. Indirect systems use ABS wheel speed sensors and need only a driver-information-center reset.
Trap
Assuming a TPMS light means a failed sensor. Verify pressures first, then sensor battery age, signal, and module codes.