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Tire sizes

275/35R20 — a 20-inch wheel and 3.79 in of tire

An aftermarket size, measured against the very different tires that happen to roll the same distance.

Metric notation · Performance and ultra-high performance

Overall diameter
27.58 in
701 mm
Section width
10.83 in
275 mm
Sidewall height
3.79 in
96 mm
Aspect ratio
35%
sidewall as a share of width
Wheel diameter
20 in
the hole in the middle
Circumference
86.6 in
2201 mm
Revolutions per mile
731.3
geometric, not measured
Revolutions per km
454.4
geometric, not measured
Typical load index
88–104
1235–1984 lb per tire

Low-profile sizes hold less air for their width, so the same vehicle weight needs a higher reference inflation. Extra Load construction is common in this class, and that is what lifts the index band — not any change in the casing size.

The load-index range shown is the band this CLASS of size is typically produced in — not a list of what is in stock for this exact size today. Load index and speed symbol are printed on the sidewall of the specific tire you are holding, and the required minimum is on the placard of the specific vehicle you are fitting. Read both.

Nearest real sizes in imperial notation, same wheel

  • 33x12.50R2033.00 in tall+5.42 in
  • 35x12.50R2035.00 in tall+7.42 in
  • 37x12.50R2037.00 in tall+9.42 in

Compare any two sizes, including ones this site has no page for, in the comparison tool.

Nothing in the vehicle records here arrives on 275/35R20 or reaches for it. That is not a comment on the size — it is a wide 35-series performance code, and the platforms it suits are outside this catalogue's coverage — but it does mean the interesting comparisons are geometric rather than historical.

Three codes at the same height, on three other wheels

Size Wheel Diameter Sidewall Section width
275/35R20 20 in 27.58 in 3.79 in 10.83 in
225/60R17 17 in 27.63 in 5.31 in 8.86 in
275/40R19 19 in 27.66 in 4.33 in 10.83 in
215/75R15 15 in 27.70 in 6.35 in 8.46 in

Twelve hundredths of an inch separates the top of that table from the bottom. Between those four rows sit a performance tire, a compact-crossover tire, a second performance tire and a light-truck size that spends most of its life on trailers.

The last row is the one worth staring at. 215/75R15 is a 15-inch code with 6.35 in of casing above the rim; this size is a 20-inch code with 3.79 in. They differ by five inches of wheel and 2.36 in of section width, and a speedometer calibrated for one would be accurate on the other to within half a per cent.

Same casing, one wheel down

275/40R19 shares this size's 10.83 in section exactly. Moving between them trades an inch of wheel for five aspect points and lands 0.08 in apart — 0.30% — with the sidewall going from 3.79 in here to 4.33 in there.

That near-cancellation is a property of the 275 mm width. Five points of aspect on a 275 casing is worth slightly more than the inch of wheel it is exchanged for, which is why the 19-inch size comes out marginally taller rather than marginally shorter. The plus sizing reference covers the general form of the trade.

Second widest of the 20-inch 35s

Within the 20-inch 35-series group this size is second widest, between 255/35R20 at 27.03 in and 285/35R20 at 27.85 in. Ten millimetres of section width is worth 0.28 in of height at this aspect ratio, so the whole four-code group — 245/35R20, 255/35R20, this size and 285/35R20 — occupies 1.10 in of diameter while spanning 1.57 in of width.

Related

Class: Performance and ultra-high performance. Every figure above is computed from the size code, not stored — see how these numbers are calculated.