205/70R14 vs 195/70R15: Tire Size Comparison, Diameter Difference & Speedometer Effect

Comparing 205/70R14 with 195/70R15 comes down to four numbers for each size: diameter, sidewall, circumference and revs per mile. 195/70R15 is the taller tire: its diameter is 654.0 mm against 642.6 mm, +11.4 mm (+1.8%) larger. The width changes by -10 mm (205 mm to 195 mm) and the sidewall by -7.0 mm. This page puts both sizes side by side, works out the diameter difference in millimetres and percent, shows the speedometer error in both directions at 30, 50 and 70 mph, and explains what the change means for ride, grip and clearance — so you can judge the swap with the actual figures in front of you.

Before the tables, keep the context straight. These are nominal new-tire dimensions, computed from the size codes: real tyres vary slightly by brand, model, wear and inflation pressure. A +1.8% 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.

205/70R14 vs 195/70R15 side by side

Measurement 205/70R14 195/70R15 Difference
Overall diameter 642.6 mm (25.3 in) 654.0 mm (25.7 in) +11.4 mm (+1.8%)
Sidewall height 143.5 mm 136.5 mm -7.0 mm
Circumference 2018.8 mm 2054.6 mm +35.8 mm
Revolutions per mile 797.2 783.3 -13.9
Section width 205 mm 195 mm -10 mm
Rim diameter 14 in 15 in +1 in

Diameter difference between 205/70R14 and 195/70R15: +11.4 mm (+1.8%)

Put the percentage in context. The plus-or-minus 3% guideline exists because small diameter changes produce small speedometer errors, and this change is +1.8%, which is inside that band. In revs per mile the shift is -13.9 (797.2 to 783.3), and in circumference it is +35.8 mm per turn. Those are not abstract figures: every mile you drive, the car covers +35.8 mm more or less per wheel revolution than the instruments expect, and the gap accumulates exactly like interest.

Speedometer error: 205/70R14 to 195/70R15 and back

The maths is a single ratio. 195/70R15 over 205/70R14 is 1.018, so every indicated speed after the swap is multiplied by that number to get the true speed: 30 becomes 30.5, 50 becomes 50.9 and 70 becomes 71.2 mph. In the reverse direction the ratio is 0.983, so 70 mph indicated is 68.8 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 195/70R15 (from 205/70R14) Actual speed fitting 205/70R14 (from 195/70R15)
30 mph 30.5 mph 29.5 mph
50 mph 50.9 mph 49.1 mph
70 mph 71.2 mph 68.8 mph

Sidewall height and ride comfort: 205/70R14 vs 195/70R15

The sidewall is where the ride difference lives. 205/70R14 has 143.5 mm of sidewall and 195/70R15 has 136.5 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 205/70R14 against 70% for 195/70R15. 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: 205/70R14 vs 195/70R15

The width gap is 10 mm (205 mm against 195 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 tire fits the rim: a 195 mm tire needs a rim width within the range its maker approves, and a rim that suited 205/70R14 may not suit 195/70R15. That is a separate check from the diameter comparison, and it belongs on the list before anything is fitted.

Revolutions per mile and gearing: 205/70R14 vs 195/70R15

Think of the gearing change as the diameter change in disguise. The revs-per-mile gap is -13.9, which is 1.8% of the original figure — the same percentage as the diameter gap. That is because revs per mile is just a mile divided by the circumference, and the circumference is pi times the diameter. So everything the gearing does — engine speed at a given road speed, acceleration in each gear, cruising refinement — shifts by 1.8% and no more. Small percentages mean small effects, which is another reason the plus-or-minus 3% guideline is a useful yardstick.

Will 195/70R15 clear after 205/70R14? What to check before fitting

Do not skip the physical check. The diameter difference is +1.8% and the width difference is -10 mm, and both of those affect whether 195/70R15 fits where 205/70R14 did. Check the gap between the tire and the arch, the gap to the suspension arms and struts, and the clearance at full steering lock in both directions. Repeat the check with weight in the car, because suspension travel changes the geometry. If the tire touches anything at any point in that check, it does not fit, whatever the diameter percentage says. The load index and speed rating need confirming against the placard too, and the rim width must suit a 195 mm tire.

Which size suits which priority: 205/70R14 or 195/70R15

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 +1.8% 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 tire that rubs is not a viable option at any percentage.

Related 205/70R14 vs 195/70R15 comparisons and tools

Frequently asked questions

What is the diameter difference between 205/70R14 and 195/70R15?

195/70R15 is +11.4 mm (+1.8%) larger in diameter than 205/70R14: 654.0 mm against 642.6 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 195/70R15 instead of 205/70R14?

For 205/70r14 vs 195/70r15 tire size comparison, the point is this: The error follows the diameter ratio, +1.8%. At an indicated 30 mph the true speed would be 30.5 mph, at 50 mph indicated it would be 50.9 mph, and at 70 mph indicated it would be 71.2 mph. The full table in both directions is in the speedometer section above.

Is 195/70R15 wider than 205/70R14, and does that matter?

No — 195/70R15 is 195 mm wide against 205 mm for 205/70R14, a difference of -10 mm. A narrower tire 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 195/70R15 fit my car if 205/70R14 fits?

Not necessarily. 195/70R15 is taller by 11.4 mm and 10 mm narrower, and it needs a 15-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 tire professional can confirm fitment on your vehicle.

Which size is better, 205/70R14 or 195/70R15?

Neither is better in general — it depends on what you want. 195/70R15 has a -7.0 mm sidewall difference, a -10 mm width difference and a +1.8% 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.