155/80R13 vs 165/70R14: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 155/80R13 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 578.2 mm, +8.4 mm (+1.5%) larger. The sidewall goes from 124.0 mm to 115.5 mm (-8.5 mm), the circumference from 1816.5 mm to 1842.9 mm, and the revs per mile from 886.0 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.

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 +1.5% 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.

155/80R13 vs 165/70R14 side by side

Measurement 155/80R13 165/70R14 Difference
Overall diameter 578.2 mm (22.8 in) 586.6 mm (23.1 in) +8.4 mm (+1.5%)
Sidewall height 124.0 mm 115.5 mm -8.5 mm
Circumference 1816.5 mm 1842.9 mm +26.4 mm
Revolutions per mile 886.0 873.3 -12.7
Section width 155 mm 165 mm +10 mm
Rim diameter 13 in 14 in +1 in

Diameter difference between 155/80R13 and 165/70R14: +8.4 mm (+1.5%)

Put the percentage in context. The plus-or-minus 3% guideline exists because small diameter changes produce small speedometer errors, and this change is +1.5%, which is inside that band. In revs per mile the shift is -12.7 (886.0 to 873.3), and in circumference it is +26.4 mm per turn. Those are not abstract figures: every mile you drive, the car covers +26.4 mm more or less per wheel revolution than the instruments expect, and the gap accumulates exactly like interest.

Speedometer error: 155/80R13 to 165/70R14 and back

The maths is a single ratio. 165/70R14 over 155/80R13 is 1.015, so every indicated speed after the swap is multiplied by that number to get the true speed: 30 becomes 30.4, 50 becomes 50.7 and 70 becomes 71.0 mph. In the reverse direction the ratio is 0.986, so 70 mph indicated is 69.0 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 165/70R14 (from 155/80R13) Actual speed fitting 155/80R13 (from 165/70R14)
30 mph 30.4 mph 29.6 mph
50 mph 50.7 mph 49.3 mph
70 mph 71.0 mph 69.0 mph

Sidewall height and ride comfort: 155/80R13 vs 165/70R14

The sidewall is where the ride difference lives. 155/80R13 has 124.0 mm of sidewall and 165/70R14 has 115.5 mm, a change of -8.5 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: 80% for 155/80R13 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: 155/80R13 vs 165/70R14

On width, the two sizes are 10 mm apart. The wider tyre (165/70R14) 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: 155/80R13 vs 165/70R14

The revs-per-mile figures (886.0 for 155/80R13, 873.3 for 165/70R14) describe the gearing effect. 165/70R14 turns -12.7 fewer times per mile, so at any given road speed the engine turns slightly slower with 165/70R14 fitted — the gearing is effectively longer. That can make cruising a touch more relaxed and can trim fuel use slightly, but it also means slightly less acceleration from the same throttle opening, because each gear is effectively taller. The change is 1.5% either way, so the effect on everyday driving is subtle rather than transformative.

Will 165/70R14 clear after 155/80R13? What to check before fitting

Whether 165/70R14 physically fits is a question for your car, not for this table. The numbers say it is taller by 8.4 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 165 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: 155/80R13 or 165/70R14

Choose on the basis of what matters to you, not on the headline alone. If ride comfort matters most, the sidewall change of -8.5 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 +1.5% 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 155/80R13 vs 165/70R14 comparisons and tools

Frequently asked questions

What is the diameter difference between 155/80R13 and 165/70R14?

165/70R14 is +8.4 mm (+1.5%) larger in diameter than 155/80R13: 586.6 mm against 578.2 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 155/80R13?

The error follows the diameter ratio, +1.5%. At an indicated 30 mph the true speed would be 30.4 mph, at 50 mph indicated it would be 50.7 mph, and at 70 mph indicated it would be 71.0 mph. The full table in both directions is in the speedometer section above. That is the point this page works through for 155/80r13 vs 165/70r14.

Is 165/70R14 wider than 155/80R13, and does that matter?

Yes — 165/70R14 is 165 mm wide against 155 mm for 155/80R13, 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 165/70R14 fit my car if 155/80R13 fits?

Not necessarily. 165/70R14 is taller by 8.4 mm and 10 mm wider, 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, 155/80R13 or 165/70R14?

Neither is better in general — it depends on what you want. 165/70R14 has a -8.5 mm sidewall difference, a +10 mm width difference and a +1.5% 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.