275/40R19 — the factory rear on an S550 Mustang
Where the 19-inch performance range stops, and what the next size up on the same wheel is actually for.
Metric notation · Performance and ultra-high performance
- Overall diameter
- 27.66 in
- 703 mm
- Section width
- 10.83 in
- 275 mm
- Sidewall height
- 4.33 in
- 110 mm
- Aspect ratio
- 40%
- sidewall as a share of width
- Wheel diameter
- 19 in
- the hole in the middle
- Circumference
- 86.9 in
- 2207 mm
- Revolutions per mile
- 729.1
- geometric, not measured
- Revolutions per km
- 453.0
- 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
Compare any two sizes, including ones this site has no page for, in the comparison tool.
Platforms recorded with this size
The sixth-generation Mustang is recorded here with 275/40R19 as a factory size. It is a rear-axle fitment on a car that runs something narrower at the front, which is the usual arrangement at this width and this wheel diameter.
The tallest of its group, by a clear margin
Six performance codes share the 19-inch wheel in this catalogue, and this is the top of them:
- 245/35R19 — 25.75 in
- 255/35R19 — 26.03 in
- 275/35R19 — 26.58 in
- 245/40R19 — 26.72 in
- 255/40R19 — 27.03 in
- 275/40R19 — 27.66 in
From bottom to top is 1.91 in, and this size accounts for the last 0.63 in of it on its own. Being both the widest section and the taller of the two aspect ratios on offer puts it at the end of the list in a way no other code on this wheel manages.
What comes next is not a bigger performance tire
Above this size the 19-inch wheel does not continue upward in small steps. The next catalogued code is 255/55R19 at 30.04 in — 2.38 in and 8.61% taller, and a crossover size rather than a performance one. Fitted in place of this tire it would take an indicated 70 mph to an actual 76.0 mph.
That is the shape of the 19-inch wheel: two separate markets sharing a bore diameter, with nothing built to sit between them because no vehicle wants a tire there.
The compact crossover that rolls the same distance
225/60R17 measures 27.63 in, three hundredths of an inch under this size, on 8.86 in of section and 5.31 in of sidewall against this size's 10.83 in and 4.33 in.
Two tires, the same rolling circumference to within a rounding error, built for a small family crossover and a rear-drive coupé respectively. Every figure a speedometer, an odometer or a gear calculation produces would be the same for both, which is a compact demonstration that overall diameter is the only dimension those calculations can see. The revolutions per mile reference works through why.
Going down instead
The aftermarket step from here is 275/35R19 at 26.58 in — the identical casing width with five aspect points removed, 1.08 in shorter, and the axle 0.54 in lower. It is the rare case of a tire change that reduces every dimension except the one being bought.
Class: Performance and ultra-high performance. Every figure above is computed from the size code, not stored — see how these numbers are calculated.