255/60R19 Tyre Size: Dimensions, Alternatives & Speedometer Effect
If you are looking up the 255/60R19 tyre size, the figures that matter are the diameter (788.6 mm, or 31.0 inches), the sidewall (153.0 mm), the circumference (2477.5 mm) and the revolutions per mile (649.6). The size code itself tells you the ingredients — 255 mm of width, an aspect ratio of 60%, a 19-inch rim — and this page shows how those ingredients combine into the measurements above, which sizes sit closest to it, and what happens to your speedometer if you fit one of them instead. Every figure here is computed from the size code, not estimated, so you can use it to check a tyre you already own or one you are thinking of buying.
People usually land on this page for one of three reasons: checking a tyre already on the car, shopping for a replacement, or wondering whether a slightly different size will work. In all three cases the approach is the same — start with the exact measurements, then compare. A 255/60R19 is a mid-width size, a tall, flexible sidewall that absorbs bumps well and suits rougher roads, at the cost of slightly softer handling, and the tables below let you hold it up against the nearest alternatives on diameter, sidewall and revs per mile. The disclaimer box just below is part of that comparison: these are calculations, and the final fitment check belongs to your placard and a tyre professional.
This is a calculation, not a safety approval. Always check your vehicle's door-jamb placard, load index and speed rating, and confirm fitment with a tyre professional before fitting a different tyre size.
What does 255/60R19 mean?
Read the code left to right. 255 means the tyre is 255 mm wide across the tread. 60 is the aspect ratio, so the sidewall is 60% of the width — 255 x 0.60 = 153.0 mm of rubber between rim and tread. R19 means it mounts on a 19-inch rim (482.6 mm). The overall diameter is the rim plus two sidewalls: 482.6 mm + 153.0 mm + 153.0 mm = 788.6 mm. Once you can do that sum, you can decode any size code you meet, and you can see why two sizes with the same rim can still be very different heights.
255/60R19 dimensions
| Measurement | Value |
|---|---|
| Overall diameter | 788.6 mm (31.0 in) |
| Sidewall height | 153.0 mm |
| Circumference | 2477.5 mm |
| Revolutions per mile | 649.6 |
| Rim diameter | 19 in |
The revs-per-mile figure, 649.6, deserves attention because it is the number your car actually senses. Speedometers and odometers count wheel revolutions and multiply by an assumed circumference; change the circumference and the maths drifts. With a 2477.5 mm circumference, this tyre turns 649.6 times per mile, and any replacement with a different circumference will turn a different number of times over the same mile. The diameter (788.6 mm, 31.0 in) and the sidewall (153.0 mm) complete the picture. Remember these are nominal new-tyre figures — real tyres vary slightly by brand, model, wear and inflation pressure, so two tyres with the same size code can differ by a millimetre or two in practice.
Closest alternative sizes to 255/60R19
The three sizes below are the closest matches to 255/60R19 in the chart, drawn from the same rim or one inch either side and ranked by diameter difference. The closest, 255/65R18, differs by +0.0% (+0.1 mm). The commonly used guideline is to stay within plus or minus 3% of the original diameter, which keeps the speedometer error small and the gearing close to standard. That guideline is about the speedometer and the car's calibration, not about whether the tyre physically clears the arches — a size can be within 3% on diameter and still rub if it is much wider, so width and clearance need their own check.
| Alternative size | Diameter | Sidewall | Diameter difference | Within ±3% guideline? |
|---|---|---|---|---|
| 255/65R18 | 788.7 mm (31.1 in) | 165.8 mm | +0.0% | Within the guideline |
| 255/55R20 | 788.5 mm (31.0 in) | 140.2 mm | -0.0% | Within the guideline |
| 275/60R18 | 787.2 mm (31.0 in) | 165.0 mm | -0.2% | Within the guideline |
Speedometer effect of changing from 255/60R19
The speedometer effect is a straight ratio. Fitting 255/65R18 (788.7 mm) in place of 255/60R19 (788.6 mm) changes the diameter by +0.0%, so every indicated speed is multiplied by 1.000 to get the real speed. At 30 mph on the dial the true speed is 30.0 mph, at 50 mph it is 50.0 mph, and at 70 mph it is 70.0 mph. The table below shows the same working for all three alternatives, so you can see at a glance which swap keeps the error negligible and which one starts to matter.
| Replacement size | Diameter change | Actual speed at 30 mph indicated | Actual speed at 50 mph indicated | Actual speed at 70 mph indicated |
|---|---|---|---|---|
| 255/65R18 | +0.0% | 30.0 mph | 50.0 mph | 70.0 mph |
| 255/55R20 | -0.0% | 30.0 mph | 50.0 mph | 70.0 mph |
| 275/60R18 | -0.2% | 29.9 mph | 49.9 mph | 69.9 mph |
Wider, narrower or taller than 255/60R19: what actually changes
Going wider than 255 mm while keeping the same aspect ratio also makes the tyre taller, because the sidewall is a percentage of the width — that is the single most common surprise in a size change. Going wider and dropping the aspect ratio keeps the diameter closer to standard, which is the idea behind plus-sizing. A taller tyre raises the car slightly and lengthens the gearing, so the engine turns a little slower at a given road speed; a shorter tyre does the opposite. Wider rubber generally brings more dry grip and more road noise, and it can increase fuel use slightly through higher rolling resistance. None of these effects is dramatic for a small change, but they all point the same way: change one dimension at a time and keep the diameter close. That is the point this page works through for 255/60r19 tyre size.
How to check 255/60R19 fits your vehicle
Start with the placard on the driver's door jamb: it lists the size, load index and speed rating the manufacturer specified for your vehicle, and it outranks whatever is currently fitted. Check that the load index of any replacement is at least the placard figure — a lower load index is not acceptable even if the size matches. Check the speed rating the same way, and check the rim width: a 255 mm tyre needs a rim within the width range the tyre maker approves for it. Then check clearance with the steering at full lock in both directions and the suspension compressed, and check the tyre-pressure monitoring system still reads correctly after the change. If any of those checks is unclear, a tyre professional can confirm fitment in minutes. The diameter being checked in this case is 788.6 mm for the 255/60R19.
Mistakes to avoid with 255/60R19
Watch for these traps. Assuming the current tyre is the correct one, instead of checking the placard. Changing width without compensating the aspect ratio, so the diameter drifts. Buying on size alone and overlooking load index and speed rating. Mixing different sizes on the same axle. And skipping the clearance check at full lock, which is exactly where a wider tyre usually makes contact. If you avoid those five, and keep the diameter within plus or minus 3% of the placard size, you have dealt with the common errors before they happen. A 255/60R19 is 255 mm wide on a 19-inch rim with a 788.6 mm overall diameter, so those are the numbers the placard check has to match.
Related 255/60R19 sizes and tools
- 255/35R19 tyre size
- 255/40R19 tyre size
- Use the Tyre Size Calculator to compare 255/60R19 against any other size.
- Use the Plus Sizing Calculator to find a wider size that keeps the diameter close to 255/60R19.
Frequently asked questions
What is the overall diameter of a 255/60R19 tyre?
The overall diameter of a new 255/60R19 tyre is 788.6 mm, which is 31.0 inches. That is the rim diameter (482.6 mm) plus twice the sidewall height (153.0 mm). It is a nominal figure, so an individual tyre can vary slightly by brand, model, wear and inflation pressure.
How tall is the sidewall on a 255/60R19 tyre?
The sidewall is 153.0 mm tall, because the aspect ratio is 60% of the 255 mm width (255 x 60/100 = 153.0 mm). A tall-sidewall sidewall like this one means a tall, flexible sidewall that absorbs bumps well and suits rougher roads, at the cost of slightly softer handling. The sidewall height is the main thing that decides how much cushioning the tyre gives over bumps.
How many revolutions per mile does a 255/60R19 tyre do?
A 255/60R19 tyre completes 649.6 revolutions per mile, based on its 2477.5 mm circumference. That figure matters because the speedometer and odometer count revolutions: fit a tyre with a different circumference and the readings drift by the same percentage as the diameter change.
What is the closest alternative size to 255/60R19?
The closest size in the chart is 255/65R18, which differs in diameter by +0.0% (+0.1 mm). The commonly used guideline is to stay within plus or minus 3% of the original diameter, and the alternative table on this page shows which sizes meet that. Diameter is only one check, though — load index, speed rating and physical clearance still need confirming.
Will changing from 255/60R19 affect my speedometer?
Yes. The speedometer assumes the original circumference, so a diameter change shifts every reading by the same percentage. Fitting 255/65R18 instead of 255/60R19 changes the diameter by +0.0%, so an indicated 70 mph would really be 70.0 mph. Keep the diameter within plus or minus 3% to keep that error small, and check the placard before fitting anything different.