175/70R13 vs 175/65R14: Tyre Size Comparison, Diameter Difference & Speedometer Effect

175/70R13 and 175/65R14 look like near neighbours on paper, but the numbers tell a more precise story. 175/65R14 is the taller tyre: its diameter is 583.1 mm against 575.2 mm, +7.9 mm (+1.4%) larger. Width moves +0 mm, sidewall height moves -8.7 mm, and the circumference changes by +24.9 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.

On this page, 175/70r13 vs 175/65r14 is the case in point: 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 +1.4% 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.

175/70R13 vs 175/65R14 side by side

Measurement 175/70R13 175/65R14 Difference
Overall diameter 575.2 mm (22.6 in) 583.1 mm (23.0 in) +7.9 mm (+1.4%)
Sidewall height 122.5 mm 113.8 mm -8.7 mm
Circumference 1807.0 mm 1831.9 mm +24.9 mm
Revolutions per mile 890.6 878.5 -12.1
Section width 175 mm 175 mm +0 mm
Rim diameter 13 in 14 in +1 in

Diameter difference between 175/70R13 and 175/65R14: +7.9 mm (+1.4%)

The diameter gap of +7.9 mm (+1.4%) 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 +24.9 mm and the revs-per-mile difference of -12.1 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 175/65R14 and back

Here is what the speedometer does in practice. Fit 175/65R14 where 175/70R13 was, and the dial understates or overstates speed by 1.4%: indicated 30 mph is really 30.4 mph, indicated 50 mph is really 50.7 mph, and indicated 70 mph is really 71.0 mph. Swap back from 175/65R14 to 175/70R13 and the error flips sign — 70 mph indicated becomes 69.1 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 175/65R14 (from 175/70R13) Actual speed fitting 175/70R13 (from 175/65R14)
30 mph 30.4 mph 29.6 mph
50 mph 50.7 mph 49.3 mph
70 mph 71.0 mph 69.1 mph

Sidewall height and ride comfort: 175/70R13 vs 175/65R14

The sidewall is where the ride difference lives. 175/70R13 has 122.5 mm of sidewall and 175/65R14 has 113.8 mm, a change of -8.7 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 65% for 175/65R14. 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 175/65R14

Width changes by +0 mm, from 175 mm to 175 mm. With the same width, the contact patch is essentially unchanged, so the grip difference between these two sizes comes from the construction and compound rather than the dimensions. Fuel use moves with rolling resistance, so a wider tyre can cost a small amount of fuel over time — the effect is real but modest for a change of this size, and it is not something this page can put a precise number on without knowing the exact tyre models involved. That is the point this page works through for 175/70r13 vs 175/65r14.

Revolutions per mile and gearing: 175/70R13 vs 175/65R14

Gearing follows the circumference. 175/65R14 covers 1831.9 mm per revolution against 1807.0 mm for 175/70R13, so it needs -12.1 fewer revolutions per mile. At a fixed road speed the engine speed drops or rises by the same 1.4% 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 175/65R14 clear after 175/70R13? What to check before fitting

Clearance is the check the numbers cannot do for you. 175/65R14 is taller and 0 mm the same width 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 175/65R14 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 175/65R14 meet what your placard asks for, and that the 14-inch rim suits the car.

Which size suits which priority: 175/70R13 or 175/65R14

The decision comes down to priorities. Comfort follows the sidewall (-8.7 mm here). Grip follows the width (+0 mm here). Instrument accuracy follows the diameter (+1.4% here). Gearing and cruising engine speed follow the revs-per-mile change (-12.1). 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 175/70R13 vs 175/65R14 comparisons and tools

Frequently asked questions

What is the diameter difference between 175/70R13 and 175/65R14?

175/65R14 is +7.9 mm (+1.4%) larger in diameter than 175/70R13: 583.1 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 175/65R14 instead of 175/70R13?

On this page, 175/70r13 vs 175/65r14 is the case in point: The error follows the diameter ratio, +1.4%. 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.

Is 175/65R14 wider than 175/70R13, and does that matter?

Neither — 175/65R14 is 175 mm wide against 175 mm for 175/70R13, a difference of +0 mm. With the same width, grip differences come from the specific tyre rather than the size. Width also affects clearance, so check the arches and suspension at full lock.

Will 175/65R14 fit my car if 175/70R13 fits?

Not necessarily. 175/65R14 is taller by 7.9 mm and 0 mm the same width, 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 175/65R14?

Neither is better in general — it depends on what you want. 175/65R14 has a -8.7 mm sidewall difference, a +0 mm width difference and a +1.4% 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.