185/60R13 vs 175/60R14: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 185/60R13 and 175/60R14, the first question is how far apart they really are. 175/60R14 is the taller tyre: its diameter is 565.6 mm against 552.2 mm, +13.4 mm (+2.4%) larger. The sidewall goes from 111.0 mm to 105.0 mm (-6.0 mm), the circumference from 1734.8 mm to 1776.9 mm, and the revs per mile from 927.7 to 905.7. The tables below lay all of that out, then work through the speedometer effect in each direction and the clearance checks that matter before either size goes on the car.

Taking 185/60r13 vs 175/60r14 tyre size comparison as the case in point: 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 +2.4% 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.

185/60R13 vs 175/60R14 side by side

Measurement 185/60R13 175/60R14 Difference
Overall diameter 552.2 mm (21.7 in) 565.6 mm (22.3 in) +13.4 mm (+2.4%)
Sidewall height 111.0 mm 105.0 mm -6.0 mm
Circumference 1734.8 mm 1776.9 mm +42.1 mm
Revolutions per mile 927.7 905.7 -22.0
Section width 185 mm 175 mm -10 mm
Rim diameter 13 in 14 in +1 in

Diameter difference between 185/60R13 and 175/60R14: +13.4 mm (+2.4%)

A +2.4% diameter change is small enough to sit inside the commonly used plus-or-minus 3% guideline, so the speedometer error it introduces stays modest. The circumference changes by +42.1 mm per revolution, and the revs per mile change by -22.0, which is the same story told from the car's point of view: the instruments count revolutions, so fewer revs per mile means the car travels further per revolution than the instruments assume. That drift also affects the odometer, so recorded mileage moves by the same percentage over time.

Speedometer error: 185/60R13 to 175/60R14 and back

Here is what the speedometer does in practice. Fit 175/60R14 where 185/60R13 was, and the dial understates or overstates speed by 2.4%: indicated 30 mph is really 30.7 mph, indicated 50 mph is really 51.2 mph, and indicated 70 mph is really 71.7 mph. Swap back from 175/60R14 to 185/60R13 and the error flips sign — 70 mph indicated becomes 68.3 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 175/60R14 (from 185/60R13) Actual speed fitting 185/60R13 (from 175/60R14)
30 mph 30.7 mph 29.3 mph
50 mph 51.2 mph 48.8 mph
70 mph 71.7 mph 68.3 mph

Sidewall height and ride comfort: 185/60R13 vs 175/60R14

The sidewall is where the ride difference lives. 185/60R13 has 111.0 mm of sidewall and 175/60R14 has 105.0 mm, a change of -6.0 mm. Less sidewall generally means sharper steering response and less cushioning, so more of the road surface reaches the cabin. The aspect ratios tell the same story in percentage terms: 60% for 185/60R13 against 60% for 175/60R14. Sidewall height also affects vulnerability to kerb damage — a shorter sidewall leaves less rubber between the rim and the road.

Width, grip and fuel use: 185/60R13 vs 175/60R14

On width, the two sizes are 10 mm apart. The narrower tyre (175/60R14) offers less rubber on the road, which tends to mean lower rolling resistance and a small fuel saving, traded against a little dry grip. Do not expect a dramatic change in fuel use from a width change of this size; the bigger influences on fuel use are the tyre compound, the pressure and the way the car is driven.

Revolutions per mile and gearing: 185/60R13 vs 175/60R14

Think of the gearing change as the diameter change in disguise. The revs-per-mile gap is -22.0, which is 2.4% 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 2.4% and no more. Small percentages mean small effects, which is another reason the plus-or-minus 3% guideline is a useful yardstick.

Will 175/60R14 clear after 185/60R13? What to check before fitting

Do not skip the physical check. The diameter difference is +2.4% and the width difference is -10 mm, and both of those affect whether 175/60R14 fits where 185/60R13 did. Check the gap between the tyre and the arch, the gap to the suspension arms and struts, and the clearance at full steering lock in both directions. Repeat the check with weight in the car, because suspension travel changes the geometry. If the tyre touches anything at any point in that check, it does not fit, whatever the diameter percentage says. The load index and speed rating need confirming against the placard too, and the rim width must suit a 175 mm tyre.

Which size suits which priority: 185/60R13 or 175/60R14

Weigh the four effects separately. Sidewall (-6.0 mm) for comfort. Width (-10 mm) for grip and rolling resistance. Diameter (+2.4%) 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 185/60R13 vs 175/60R14 comparisons and tools

Frequently asked questions

What is the diameter difference between 185/60R13 and 175/60R14?

175/60R14 is +13.4 mm (+2.4%) larger in diameter than 185/60R13: 565.6 mm against 552.2 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 175/60R14 instead of 185/60R13?

The error follows the diameter ratio, +2.4%. At an indicated 30 mph the true speed would be 30.7 mph, at 50 mph indicated it would be 51.2 mph, and at 70 mph indicated it would be 71.7 mph. The full table in both directions is in the speedometer section above. That is the point this page works through for 185/60r13 vs 175/60r14 tyre size comparison.

Is 175/60R14 wider than 185/60R13, and does that matter?

No — 175/60R14 is 175 mm wide against 185 mm for 185/60R13, a difference of -10 mm. A narrower tyre generally gives less rolling resistance and can behave better in standing water, with slightly less dry grip. Width also affects clearance, so check the arches and suspension at full lock.

Will 175/60R14 fit my car if 185/60R13 fits?

Not necessarily. 175/60R14 is taller by 13.4 mm and 10 mm narrower, 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, 185/60R13 or 175/60R14?

Neither is better in general — it depends on what you want. 175/60R14 has a -6.0 mm sidewall difference, a -10 mm width difference and a +2.4% 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.