285/30R21 Tire Size Specifications & Compatible Vehicles
Overall Diameter
704.4 mm
Section Width
285 mm
Sidewall Height
85.5 mm
Circumference
2212.9 mm
Revs/Mile
727
Rim Diameter
21"
Inch Equivalent
27.7x11.2R21
Rim Width (ETRTO)
8.5" – 11.0"
Alternative Tire Sizes
These tire sizes are within 3% overall diameter of 285/30R21 and may be used as replacements:
Understanding 285/30R21
The tire size 285/30R21 means the tire has a section width of 285mm, an aspect ratio of 30% (the sidewall height is 30% of the width), and fits a 21-inch rim.
Sidewall Height = 285 x 0.3 = 85.5 mm
Overall Diameter = (85.5 x 2) + (21 x 25.4) = 704.4 mm
Circumference = 704.4 x π = 2212.9 mm
Overall Diameter = (85.5 x 2) + (21 x 25.4) = 704.4 mm
Circumference = 704.4 x π = 2212.9 mm
Frequently Asked Questions
The 285/30R21 is a standard tire size. Check your vehicle door jamb sticker or owner manual to confirm compatibility.
A 285/30R21 tire has an overall diameter of 704.4mm (27.7 inches). The sidewall height is 85.5mm, and the total circumference is 2213mm.
For 285/30R21 tires, the ETRTO recommended rim width is 9.5". The acceptable range is 8.5" minimum to 11.0" maximum. Using a rim outside this range can cause improper bead seating and unsafe handling.
Yes, as long as the replacement tire overall diameter is within 3% of the 285/30R21 704.4mm diameter. Compatible alternatives include 185/60R19, 245/40R20, 155/55R21. Use our Tire Size Calculator to compare any two sizes.