165/70R13 vs 185/60R13: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 165/70R13 and 185/60R13, the first question is how far apart they really are. 185/60R13 is the shorter tyre: its diameter is 552.2 mm against 561.2 mm, -9.0 mm (-1.6%) smaller. The sidewall goes from 115.5 mm to 111.0 mm (-4.5 mm), the circumference from 1763.1 mm to 1734.8 mm, and the revs per mile from 912.8 to 927.7. 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.

The short version: a -1.6% 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 20 mm and in rim size (13 inches against 13 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.

165/70R13 vs 185/60R13 side by side

Measurement 165/70R13 185/60R13 Difference
Overall diameter 561.2 mm (22.1 in) 552.2 mm (21.7 in) -9.0 mm (-1.6%)
Sidewall height 115.5 mm 111.0 mm -4.5 mm
Circumference 1763.1 mm 1734.8 mm -28.3 mm
Revolutions per mile 912.8 927.7 +14.9
Section width 165 mm 185 mm +20 mm
Rim diameter 13 in 13 in +0 in

Diameter difference between 165/70R13 and 185/60R13: -9.0 mm (-1.6%)

The diameter gap of -9.0 mm (-1.6%) 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 -28.3 mm and the revs-per-mile difference of +14.9 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: 165/70R13 to 185/60R13 and back

Going from 165/70R13 to 185/60R13, the diameter grows by -1.6%, so the true speed is the indicated speed multiplied by 0.984. At 30 mph on the dial the car is really doing 29.5 mph; at 50 mph indicated it is 49.2 mph; at 70 mph indicated it is 68.9 mph. The speedometer therefore reads high 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 185/60R13 back to 165/70R13, the error reverses exactly: the ratio becomes 1.016, so 70 mph indicated is really 71.1 mph.

Indicated speed Actual speed fitting 185/60R13 (from 165/70R13) Actual speed fitting 165/70R13 (from 185/60R13)
30 mph 29.5 mph 30.5 mph
50 mph 49.2 mph 50.8 mph
70 mph 68.9 mph 71.1 mph

Sidewall height and ride comfort: 165/70R13 vs 185/60R13

The sidewall is where the ride difference lives. 165/70R13 has 115.5 mm of sidewall and 185/60R13 has 111.0 mm, a change of -4.5 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: 70% for 165/70R13 against 60% for 185/60R13. 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: 165/70R13 vs 185/60R13

On width, the two sizes are 20 mm apart. The wider tyre (185/60R13) 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: 165/70R13 vs 185/60R13

Gearing follows the circumference. 185/60R13 covers 1734.8 mm per revolution against 1763.1 mm for 165/70R13, so it needs +14.9 fewer revolutions per mile. At a fixed road speed the engine speed drops or rises by the same 1.6% as the diameter change. With the shorter size the engine sits slightly higher in the rev range at cruising speed, which sharpens response a little at the cost of a small amount of fuel. Either way the effect is proportional to the diameter difference, not larger than it.

Will 185/60R13 clear after 165/70R13? What to check before fitting

Whether 185/60R13 physically fits is a question for your car, not for this table. The numbers say it is shorter by 9.0 mm and 20 mm wider, and those are the dimensions that decide clearance — but the actual gaps depend on your arches, suspension and steering geometry. Check at full lock both ways, check with the suspension compressed, and check with the car loaded. Check the placard for the load index and speed rating, and check the rim width for a 185 mm tyre. A tyre professional can confirm all of it in one visit, and that confirmation is the step that turns a comparison into a fitment.

Which size suits which priority: 165/70R13 or 185/60R13

Choose on the basis of what matters to you, not on the headline alone. If ride comfort matters most, the sidewall change of -4.5 mm is the figure to weigh. If grip matters most, the width change of +20 mm is the one to weigh. If keeping the instruments accurate matters most, the diameter change of -1.6% 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 165/70R13 vs 185/60R13 comparisons and tools

Frequently asked questions

What is the diameter difference between 165/70R13 and 185/60R13?

185/60R13 is -9.0 mm (-1.6%) smaller in diameter than 165/70R13: 552.2 mm against 561.2 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 185/60R13 instead of 165/70R13?

The error follows the diameter ratio, -1.6%. At an indicated 30 mph the true speed would be 29.5 mph, at 50 mph indicated it would be 49.2 mph, and at 70 mph indicated it would be 68.9 mph. The full table in both directions is in the speedometer section above. That is the point this page works through for 165/70r13 vs 185/60r13 tyre size comparison.

Is 185/60R13 wider than 165/70R13, and does that matter?

Yes — 185/60R13 is 185 mm wide against 165 mm for 165/70R13, 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 185/60R13 fit my car if 165/70R13 fits?

Not necessarily. 185/60R13 is shorter by 9.0 mm and 20 mm wider, and it needs a 13-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, 165/70R13 or 185/60R13?

Neither is better in general — it depends on what you want. 185/60R13 has a -4.5 mm sidewall difference, a +20 mm width difference and a -1.6% 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.