165/70R15 vs 175/60R16: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 165/70R15 and 175/60R16, the first question is how far apart they really are. 175/60R16 is the taller tyre: its diameter is 616.4 mm against 612.0 mm, +4.4 mm (+0.7%) larger. The sidewall goes from 115.5 mm to 105.0 mm (-10.5 mm), the circumference from 1922.7 mm to 1936.5 mm, and the revs per mile from 837.0 to 831.1. 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 +0.7% 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.

165/70R15 vs 175/60R16 side by side

Measurement 165/70R15 175/60R16 Difference
Overall diameter 612.0 mm (24.1 in) 616.4 mm (24.3 in) +4.4 mm (+0.7%)
Sidewall height 115.5 mm 105.0 mm -10.5 mm
Circumference 1922.7 mm 1936.5 mm +13.8 mm
Revolutions per mile 837.0 831.1 -5.9
Section width 165 mm 175 mm +10 mm
Rim diameter 15 in 16 in +1 in

Diameter difference between 165/70R15 and 175/60R16: +4.4 mm (+0.7%)

Put the percentage in context. The plus-or-minus 3% guideline exists because small diameter changes produce small speedometer errors, and this change is +0.7%, which is inside that band. In revs per mile the shift is -5.9 (837.0 to 831.1), and in circumference it is +13.8 mm per turn. Those are not abstract figures: every mile you drive, the car covers +13.8 mm more or less per wheel revolution than the instruments expect, and the gap accumulates exactly like interest.

Speedometer error: 165/70R15 to 175/60R16 and back

The maths is a single ratio. 175/60R16 over 165/70R15 is 1.007, so every indicated speed after the swap is multiplied by that number to get the true speed: 30 becomes 30.2, 50 becomes 50.4 and 70 becomes 70.5 mph. In the reverse direction the ratio is 0.993, so 70 mph indicated is 69.5 mph in reality. The table below shows both directions at all three speeds, so you can check whichever direction applies to your car without doing the arithmetic yourself.

Indicated speed Actual speed fitting 175/60R16 (from 165/70R15) Actual speed fitting 165/70R15 (from 175/60R16)
30 mph 30.2 mph 29.8 mph
50 mph 50.4 mph 49.6 mph
70 mph 70.5 mph 69.5 mph

Sidewall height and ride comfort: 165/70R15 vs 175/60R16

The sidewall is where the ride difference lives. 165/70R15 has 115.5 mm of sidewall and 175/60R16 has 105.0 mm, a change of -10.5 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 165/70R15 against 60% for 175/60R16. 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: 165/70R15 vs 175/60R16

The width gap is 10 mm (165 mm against 175 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 175 mm tyre needs a rim width within the range its maker approves, and a rim that suited 165/70R15 may not suit 175/60R16. That is a separate check from the diameter comparison, and it belongs on the list before anything is fitted.

Revolutions per mile and gearing: 165/70R15 vs 175/60R16

Gearing follows the circumference. 175/60R16 covers 1936.5 mm per revolution against 1922.7 mm for 165/70R15, so it needs -5.9 fewer revolutions per mile. At a fixed road speed the engine speed drops or rises by the same 0.7% as the diameter change. With the taller size the engine sits slightly lower in the rev range at cruising speed, which some drivers like and which can help fuel use a little. Either way the effect is proportional to the diameter difference, not larger than it.

Will 175/60R16 clear after 165/70R15? What to check before fitting

Whether 175/60R16 physically fits is a question for your car, not for this table. The numbers say it is taller by 4.4 mm and 10 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 175 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: 165/70R15 or 175/60R16

Choose on the basis of what matters to you, not on the headline alone. If ride comfort matters most, the sidewall change of -10.5 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 +0.7% 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 165/70R15 vs 175/60R16 comparisons and tools

Frequently asked questions

What is the diameter difference between 165/70R15 and 175/60R16?

175/60R16 is +4.4 mm (+0.7%) larger in diameter than 165/70R15: 616.4 mm against 612.0 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 175/60R16 instead of 165/70R15?

For 165/70r15 vs 175/60r16, the point is this: The error follows the diameter ratio, +0.7%. At an indicated 30 mph the true speed would be 30.2 mph, at 50 mph indicated it would be 50.4 mph, and at 70 mph indicated it would be 70.5 mph. The full table in both directions is in the speedometer section above.

Is 175/60R16 wider than 165/70R15, and does that matter?

Yes — 175/60R16 is 175 mm wide against 165 mm for 165/70R15, 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 175/60R16 fit my car if 165/70R15 fits?

Not necessarily. 175/60R16 is taller by 4.4 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, 165/70R15 or 175/60R16?

Neither is better in general — it depends on what you want. 175/60R16 has a -10.5 mm sidewall difference, a +10 mm width difference and a +0.7% 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.