175/70R13 vs 165/70R14: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 175/70R13 and 165/70R14, the first question is how far apart they really are. 165/70R14 is the taller tyre: its diameter is 586.6 mm against 575.2 mm, +11.4 mm (+2.0%) larger. The sidewall goes from 122.5 mm to 115.5 mm (-7.0 mm), the circumference from 1807.0 mm to 1842.9 mm, and the revs per mile from 890.6 to 873.3. 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.

Two things decide whether this swap makes sense: the diameter difference and the physical fit. On diameter, 165/70R14 is +2.0% larger than 175/70R13, which is inside the plus-or-minus 3% guideline. On physical fit, the width change of -10 mm and the rim change from 13 to 14 inches both need checking against the arches, suspension and steering lock. The sections below take each of those in turn, with the numbers worked out rather than asserted.

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.

175/70R13 vs 165/70R14 side by side

Measurement 175/70R13 165/70R14 Difference
Overall diameter 575.2 mm (22.6 in) 586.6 mm (23.1 in) +11.4 mm (+2.0%)
Sidewall height 122.5 mm 115.5 mm -7.0 mm
Circumference 1807.0 mm 1842.9 mm +35.9 mm
Revolutions per mile 890.6 873.3 -17.3
Section width 175 mm 165 mm -10 mm
Rim diameter 13 in 14 in +1 in

Diameter difference between 175/70R13 and 165/70R14: +11.4 mm (+2.0%)

The diameter gap of +11.4 mm (+2.0%) 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 +35.9 mm and the revs-per-mile difference of -17.3 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: 175/70R13 to 165/70R14 and back

Going from 175/70R13 to 165/70R14, the diameter grows by +2.0%, so the true speed is the indicated speed multiplied by 1.020. At 30 mph on the dial the car is really doing 30.6 mph; at 50 mph indicated it is 51.0 mph; at 70 mph indicated it is 71.4 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 165/70R14 back to 175/70R13, the error reverses exactly: the ratio becomes 0.981, so 70 mph indicated is really 68.6 mph.

Indicated speed Actual speed fitting 165/70R14 (from 175/70R13) Actual speed fitting 175/70R13 (from 165/70R14)
30 mph 30.6 mph 29.4 mph
50 mph 51.0 mph 49.0 mph
70 mph 71.4 mph 68.6 mph

Sidewall height and ride comfort: 175/70R13 vs 165/70R14

The sidewall is where the ride difference lives. 175/70R13 has 122.5 mm of sidewall and 165/70R14 has 115.5 mm, a change of -7.0 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: 70% for 175/70R13 against 70% for 165/70R14. 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: 175/70R13 vs 165/70R14

The width gap is 10 mm (175 mm against 165 mm). Going narrower usually trims rolling resistance and can improve behaviour in standing water, and it costs a little in dry grip. Remember that width also decides whether the tyre fits the rim: a 165 mm tyre needs a rim width within the range its maker approves, and a rim that suited 175/70R13 may not suit 165/70R14. That is a separate check from the diameter comparison, and it belongs on the list before anything is fitted.

Revolutions per mile and gearing: 175/70R13 vs 165/70R14

Gearing follows the circumference. 165/70R14 covers 1842.9 mm per revolution against 1807.0 mm for 175/70R13, so it needs -17.3 fewer revolutions per mile. At a fixed road speed the engine speed drops or rises by the same 2.0% 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 165/70R14 clear after 175/70R13? What to check before fitting

Clearance is the check the numbers cannot do for you. 165/70R14 is taller and 10 mm narrower than 175/70R13, so check the wheel arches, the suspension components and the steering lock: turn the wheel fully in both directions and check for contact, and check again with the suspension compressed and the car loaded as it will actually be used. A size that clears when the car is stationary and unloaded can still rub over a bump or at full lock. This page does not claim that 165/70R14 clears your car, and no diameter table can — only a physical check on your vehicle can confirm it. Also confirm the load index and speed rating of 165/70R14 meet what your placard asks for, and that the 14-inch rim suits the car.

Which size suits which priority: 175/70R13 or 165/70R14

For 175/70r13 vs 165/70r14, the point is this: Choose on the basis of what matters to you, not on the headline alone. If ride comfort matters most, the sidewall change of -7.0 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 +2.0% 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 175/70R13 vs 165/70R14 comparisons and tools

Frequently asked questions

What is the diameter difference between 175/70R13 and 165/70R14?

165/70R14 is +11.4 mm (+2.0%) larger in diameter than 175/70R13: 586.6 mm against 575.2 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 165/70R14 instead of 175/70R13?

Taking 175/70r13 vs 165/70r14 as the case in point: The error follows the diameter ratio, +2.0%. At an indicated 30 mph the true speed would be 30.6 mph, at 50 mph indicated it would be 51.0 mph, and at 70 mph indicated it would be 71.4 mph. The full table in both directions is in the speedometer section above.

Is 165/70R14 wider than 175/70R13, and does that matter?

No — 165/70R14 is 165 mm wide against 175 mm for 175/70R13, 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 165/70R14 fit my car if 175/70R13 fits?

Not necessarily. 165/70R14 is taller by 11.4 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, 175/70R13 or 165/70R14?

Neither is better in general — it depends on what you want. 165/70R14 has a -7.0 mm sidewall difference, a -10 mm width difference and a +2.0% 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.