185/70R14 vs 195/60R15: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 185/70R14 and 195/60R15, the first question is how far apart they really are. 195/60R15 is the taller tyre: its diameter is 615.0 mm against 614.6 mm, +0.4 mm (+0.1%) larger. The sidewall goes from 129.5 mm to 117.0 mm (-12.5 mm), the circumference from 1930.8 mm to 1932.1 mm, and the revs per mile from 833.5 to 833.0. 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.

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 +0.1% 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 195/60R15 side by side

Measurement 185/70R14 195/60R15 Difference
Overall diameter 614.6 mm (24.2 in) 615.0 mm (24.2 in) +0.4 mm (+0.1%)
Sidewall height 129.5 mm 117.0 mm -12.5 mm
Circumference 1930.8 mm 1932.1 mm +1.3 mm
Revolutions per mile 833.5 833.0 -0.5
Section width 185 mm 195 mm +10 mm
Rim diameter 14 in 15 in +1 in

Diameter difference between 185/70R14 and 195/60R15: +0.4 mm (+0.1%)

A +0.1% 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 +1.3 mm per revolution, and the revs per mile change by -0.5, 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: 185/70R14 to 195/60R15 and back

Going from 185/70R14 to 195/60R15, the diameter grows by +0.1%, so the true speed is the indicated speed multiplied by 1.001. At 30 mph on the dial the car is really doing 30.0 mph; at 50 mph indicated it is 50.0 mph; at 70 mph indicated it is 70.0 mph. The speedometer therefore reads low after the change, which matters most at motorway speed, where even a small percentage is a real difference in miles per hour. Going the other way, from 195/60R15 back to 185/70R14, the error reverses exactly: the ratio becomes 0.999, so 70 mph indicated is really 70.0 mph.

Indicated speed Actual speed fitting 195/60R15 (from 185/70R14) Actual speed fitting 185/70R14 (from 195/60R15)
30 mph 30.0 mph 30.0 mph
50 mph 50.0 mph 50.0 mph
70 mph 70.0 mph 70.0 mph

Sidewall height and ride comfort: 185/70R14 vs 195/60R15

Sidewall height moves by -12.5 mm between these two sizes (129.5 mm to 117.0 mm), and that is enough to feel. A taller sidewall flexes more, which softens sharp impacts and gives the tyre more give over potholes; a shorter sidewall flexes less, which sharpens the steering response and leaves the rim closer to the road surface on a hard hit. Which of those you get depends on the direction of the change — here the sidewall shrinks — and on the aspect ratio shift from 70% to 60%. That is the point this page works through for 185/70r14 vs 195/60r15.

Width, grip and fuel use: 185/70R14 vs 195/60R15

On width, the two sizes are 10 mm apart. The wider tyre (195/60R15) offers more rubber on the road, which tends to mean more grip in the dry and slightly more resistance to roll. 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: 185/70R14 vs 195/60R15

On this page, 185/70r14 vs 195/60r15 is the case in point: Think of the gearing change as the diameter change in disguise. The revs-per-mile gap is -0.5, which is 0.1% 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 0.1% and no more. Small percentages mean small effects, which is another reason the plus-or-minus 3% guideline is a useful yardstick.

Will 195/60R15 clear after 185/70R14? What to check before fitting

Do not skip the physical check. The diameter difference is +0.1% and the width difference is +10 mm, and both of those affect whether 195/60R15 fits where 185/70R14 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 195 mm tyre.

Which size suits which priority: 185/70R14 or 195/60R15

Choose on the basis of what matters to you, not on the headline alone. If ride comfort matters most, the sidewall change of -12.5 mm is the figure to weigh. If grip matters most, the width change of +10 mm is the one to weigh. If keeping the instruments accurate matters most, the diameter change of +0.1% is the one to weigh — and if it is outside the plus-or-minus 3% guideline, ask about recalibration. And if the answer to the clearance check is uncertain, that outranks all three: a tyre that rubs is not a viable option at any percentage.

Related 185/70R14 vs 195/60R15 comparisons and tools

Frequently asked questions

What is the diameter difference between 185/70R14 and 195/60R15?

195/60R15 is +0.4 mm (+0.1%) larger in diameter than 185/70R14: 615.0 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 195/60R15 instead of 185/70R14?

The error follows the diameter ratio, +0.1%. At an indicated 30 mph the true speed would be 30.0 mph, at 50 mph indicated it would be 50.0 mph, and at 70 mph indicated it would be 70.0 mph. The full table in both directions is in the speedometer section above. That is the point this page works through for 185/70r14 vs 195/60r15.

Is 195/60R15 wider than 185/70R14, and does that matter?

Yes — 195/60R15 is 195 mm wide against 185 mm for 185/70R14, a difference of +10 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 195/60R15 fit my car if 185/70R14 fits?

Not necessarily. 195/60R15 is taller by 0.4 mm and 10 mm wider, and it needs a 15-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 195/60R15?

Neither is better in general — it depends on what you want. 195/60R15 has a -12.5 mm sidewall difference, a +10 mm width difference and a +0.1% 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.