185/70R15 vs 195/60R16: Tyre Size Comparison, Diameter Difference & Speedometer Effect

185/70R15 and 195/60R16 look like near neighbours on paper, but the numbers tell a more precise story. 195/60R16 is the taller tyre: its diameter is 640.4 mm against 640.0 mm, +0.4 mm (+0.1%) larger. Width moves +10 mm, sidewall height moves -12.5 mm, and the circumference changes by +1.3 mm, which is what the speedometer feels. This comparison works through the side-by-side measurements, the speedometer error at 30, 50 and 70 mph in both directions, and the practical effects on ride comfort, grip and wheel-arch clearance.

The short version: a +0.1% diameter difference is inside the commonly used plus-or-minus 3% guideline, which is the usual yardstick for keeping speedometer error small. But diameter is only the first check. The two sizes also differ in width by 10 mm and in rim size (15 inches against 16 inches), so a swap means different wheels as well unless the rims already match. Read the whole comparison before deciding — the clearance and load-index sections matter as much as the headline percentage.

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.

185/70R15 vs 195/60R16 side by side

Measurement 185/70R15 195/60R16 Difference
Overall diameter 640.0 mm (25.2 in) 640.4 mm (25.2 in) +0.4 mm (+0.1%)
Sidewall height 129.5 mm 117.0 mm -12.5 mm
Circumference 2010.6 mm 2011.9 mm +1.3 mm
Revolutions per mile 800.4 799.9 -0.5
Section width 185 mm 195 mm +10 mm
Rim diameter 15 in 16 in +1 in

Diameter difference between 185/70R15 and 195/60R16: +0.4 mm (+0.1%)

The diameter gap of +0.4 mm (+0.1%) 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 +1.3 mm and the revs-per-mile difference of -0.5 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: 185/70R15 to 195/60R16 and back

Here is what the speedometer does in practice. Fit 195/60R16 where 185/70R15 was, and the dial understates or overstates speed by 0.1%: indicated 30 mph is really 30.0 mph, indicated 50 mph is really 50.0 mph, and indicated 70 mph is really 70.0 mph. Swap back from 195/60R16 to 185/70R15 and the error flips sign — 70 mph indicated becomes 70.0 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 195/60R16 (from 185/70R15) Actual speed fitting 185/70R15 (from 195/60R16)
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: 185/70R15 vs 195/60R16

Look at the sidewalls next. 129.5 mm on 185/70R15, 117.0 mm on 195/60R16: a difference of -12.5 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: 185/70R15 vs 195/60R16

On width, the two sizes are 10 mm apart. The wider tyre (195/60R16) 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: 185/70R15 vs 195/60R16

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. That is the point this page works through for 185/70r15 vs 195/60r16.

Will 195/60R16 clear after 185/70R15? 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 195/60R16 fits where 185/70R15 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: 185/70R15 or 195/60R16

The decision comes down to priorities. Comfort follows the sidewall (-12.5 mm here). Grip follows the width (+10 mm here). Instrument accuracy follows the diameter (+0.1% here). Gearing and cruising engine speed follow the revs-per-mile change (-0.5). None of those is large in this comparison, which is why the practical checks — clearance, load index, speed rating, rim width — deserve as much attention as the numbers. Get those right and the size choice becomes a matter of preference rather than a risk.

Related 185/70R15 vs 195/60R16 comparisons and tools

Frequently asked questions

What is the diameter difference between 185/70R15 and 195/60R16?

195/60R16 is +0.4 mm (+0.1%) larger in diameter than 185/70R15: 640.4 mm against 640.0 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 195/60R16 instead of 185/70R15?

For 185/70r15 vs 195/60r16, the point is this: 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.

Is 195/60R16 wider than 185/70R15, and does that matter?

Yes — 195/60R16 is 195 mm wide against 185 mm for 185/70R15, 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 195/60R16 fit my car if 185/70R15 fits?

Not necessarily. 195/60R16 is taller by 0.4 mm and 10 mm wider, and it needs a 16-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, 185/70R15 or 195/60R16?

Neither is better in general — it depends on what you want. 195/60R16 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.