185/70R14 vs 205/60R14: Tyre Size Comparison, Diameter Difference & Speedometer Effect

Comparing 185/70R14 with 205/60R14 comes down to four numbers for each size: diameter, sidewall, circumference and revs per mile. 205/60R14 is the shorter tyre: its diameter is 601.6 mm against 614.6 mm, -13.0 mm (-2.1%) smaller. The width changes by +20 mm (185 mm to 205 mm) and the sidewall by -6.5 mm. This page puts both sizes side by side, works out the diameter difference in millimetres and percent, shows the speedometer error in both directions at 30, 50 and 70 mph, and explains what the change means for ride, grip and clearance — so you can judge the swap with the actual figures in front of you.

Before the tables, keep the context straight. These are nominal new-tyre dimensions, computed from the size codes: real tyres vary slightly by brand, model, wear and inflation pressure. A -2.1% difference is within the plus-or-minus 3% guideline that is commonly used for speedometer accuracy, and the speedometer tables below show exactly what that percentage means at real road speeds. The rest of the page covers sidewall, grip, gearing and the clearance checks that decide whether the larger size can physically fit.

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.

185/70R14 vs 205/60R14 side by side

Measurement 185/70R14 205/60R14 Difference
Overall diameter 614.6 mm (24.2 in) 601.6 mm (23.7 in) -13.0 mm (-2.1%)
Sidewall height 129.5 mm 123.0 mm -6.5 mm
Circumference 1930.8 mm 1890.0 mm -40.8 mm
Revolutions per mile 833.5 851.5 +18.0
Section width 185 mm 205 mm +20 mm
Rim diameter 14 in 14 in +0 in

Diameter difference between 185/70R14 and 205/60R14: -13.0 mm (-2.1%)

The diameter gap of -13.0 mm (-2.1%) is the number to carry away from this section. It is inside the plus-or-minus 3% guideline, and it shows up directly in the speedometer tables below. The circumference difference of -40.8 mm and the revs-per-mile difference of +18.0 are the same change expressed differently — the first is what the road sees, the second is what the car's sensors count. Neither is a safety judgement on its own; both are inputs to the fitment checks further down the page.

Speedometer error: 185/70R14 to 205/60R14 and back

Here is what the speedometer does in practice. Fit 205/60R14 where 185/70R14 was, and the dial understates or overstates speed by 2.1%: indicated 30 mph is really 29.4 mph, indicated 50 mph is really 48.9 mph, and indicated 70 mph is really 68.5 mph. Swap back from 205/60R14 to 185/70R14 and the error flips sign — 70 mph indicated becomes 71.5 mph. The odometer drifts by the same percentage in each direction, so recorded mileage and any service intervals based on it shift too.

Indicated speed Actual speed fitting 205/60R14 (from 185/70R14) Actual speed fitting 185/70R14 (from 205/60R14)
30 mph 29.4 mph 30.6 mph
50 mph 48.9 mph 51.1 mph
70 mph 68.5 mph 71.5 mph

Sidewall height and ride comfort: 185/70R14 vs 205/60R14

Look at the sidewalls next. 129.5 mm on 185/70R14, 123.0 mm on 205/60R14: a difference of -6.5 mm. That is the flexible part of the tyre, and it is the first thing that absorbs a bump. A shorter sidewall transmits more of the road to the driver, which feels more direct but less forgiving on rough surfaces. Aspect ratio (70% vs 60%) is simply the sidewall expressed as a share of the width.

Width, grip and fuel use: 185/70R14 vs 205/60R14

The width gap is 20 mm (185 mm against 205 mm). Going wider usually buys dry grip and a more planted feel, and it costs a little in rolling resistance and road noise. Remember that width also decides whether the tyre fits the rim: a 205 mm tyre needs a rim width within the range its maker approves, and a rim that suited 185/70R14 may not suit 205/60R14. That is a separate check from the diameter comparison, and it belongs on the list before anything is fitted.

Revolutions per mile and gearing: 185/70R14 vs 205/60R14

Think of the gearing change as the diameter change in disguise. The revs-per-mile gap is +18.0, which is 2.1% of the original figure — the same percentage as the diameter gap. That is because revs per mile is just a mile divided by the circumference, and the circumference is pi times the diameter. So everything the gearing does — engine speed at a given road speed, acceleration in each gear, cruising refinement — shifts by 2.1% and no more. Small percentages mean small effects, which is another reason the plus-or-minus 3% guideline is a useful yardstick.

Will 205/60R14 clear after 185/70R14? What to check before fitting

Clearance is the check the numbers cannot do for you. 205/60R14 is shorter and 20 mm wider than 185/70R14, so check the wheel arches, the suspension components and the steering lock: turn the wheel fully in both directions and check for contact, and check again with the suspension compressed and the car loaded as it will actually be used. A size that clears when the car is stationary and unloaded can still rub over a bump or at full lock. This page does not claim that 205/60R14 clears your car, and no diameter table can — only a physical check on your vehicle can confirm it. Also confirm the load index and speed rating of 205/60R14 meet what your placard asks for, and that the 14-inch rim suits the car.

Which size suits which priority: 185/70R14 or 205/60R14

Weigh the four effects separately. Sidewall (-6.5 mm) for comfort. Width (+20 mm) for grip and rolling resistance. Diameter (-2.1%) for the speedometer, odometer and gearing. And clearance for whether the swap is physically possible at all. If the diameter is inside the plus-or-minus 3% guideline and the clearance check passes, the remaining differences are small enough to be a matter of taste; if either of those fails, the comparison is academic until it is resolved.

Related 185/70R14 vs 205/60R14 comparisons and tools

Frequently asked questions

What is the diameter difference between 185/70R14 and 205/60R14?

205/60R14 is -13.0 mm (-2.1%) smaller in diameter than 185/70R14: 601.6 mm against 614.6 mm. That is inside the commonly used plus-or-minus 3% guideline for keeping speedometer error small.

How much will my speedometer be out if I fit 205/60R14 instead of 185/70R14?

Taking 185/70r14 vs 205/60r14 tyre size comparison as the case in point: The error follows the diameter ratio, -2.1%. At an indicated 30 mph the true speed would be 29.4 mph, at 50 mph indicated it would be 48.9 mph, and at 70 mph indicated it would be 68.5 mph. The full table in both directions is in the speedometer section above.

Is 205/60R14 wider than 185/70R14, and does that matter?

Yes — 205/60R14 is 205 mm wide against 185 mm for 185/70R14, a difference of +20 mm. A wider tyre generally gives more dry grip and can increase rolling resistance and road noise slightly. Width also affects clearance, so check the arches and suspension at full lock.

Will 205/60R14 fit my car if 185/70R14 fits?

Not necessarily. 205/60R14 is shorter by 13.0 mm and 20 mm wider, and it needs a 14-inch rim. Check the wheel arches, suspension and steering lock at full lock in both directions, with the car loaded, and confirm the load index and speed rating against your door-jamb placard. A tyre professional can confirm fitment on your vehicle.

Which size is better, 185/70R14 or 205/60R14?

Neither is better in general — it depends on what you want. 205/60R14 has a -6.5 mm sidewall difference, a +20 mm width difference and a -2.1% diameter difference, so the trade-offs are comfort, grip and instrument accuracy respectively. If the diameter is within the plus-or-minus 3% guideline and the clearance check passes, the choice is a matter of preference; if not, resolve those two points first.