305/35R21 Tire Size Specifications & Compatible Vehicles
Overall Diameter
746.9 mm
Section Width
305 mm
Sidewall Height
106.8 mm
Circumference
2346.5 mm
Revs/Mile
686
Rim Diameter
21"
Inch Equivalent
29.4x12R21
Rim Width (ETRTO)
9.5" – 12.0"
Alternative Tire Sizes
These tire sizes are within 3% overall diameter of 305/35R21 and may be used as replacements:
Understanding 305/35R21
The tire size 305/35R21 means the tire has a section width of 305mm, an aspect ratio of 35% (the sidewall height is 35% of the width), and fits a 21-inch rim.
Sidewall Height = 305 x 0.35 = 106.8 mm
Overall Diameter = (106.8 x 2) + (21 x 25.4) = 746.9 mm
Circumference = 746.9 x π = 2346.5 mm
Overall Diameter = (106.8 x 2) + (21 x 25.4) = 746.9 mm
Circumference = 746.9 x π = 2346.5 mm
Frequently Asked Questions
The 305/35R21 is a standard tire size. Check your vehicle door jamb sticker or owner manual to confirm compatibility.
A 305/35R21 tire has an overall diameter of 746.9mm (29.4 inches). The sidewall height is 106.8mm, and the total circumference is 2347mm.
For 305/35R21 tires, the ETRTO recommended rim width is 10.5". The acceptable range is 9.5" minimum to 12.0" 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 305/35R21 746.9mm diameter. Compatible alternatives include 235/40R22, 165/80R19, 265/45R20. Use our Tire Size Calculator to compare any two sizes.