215/70R14 vs 205/70R15: Tyre Size Comparison, Diameter Difference & Speedometer Effect

If you are choosing between 215/70R14 and 205/70R15, the first question is how far apart they really are. 205/70R15 is the taller tyre: its diameter is 668.0 mm against 656.6 mm, +11.4 mm (+1.7%) larger. The sidewall goes from 150.5 mm to 143.5 mm (-7.0 mm), the circumference from 2062.8 mm to 2098.6 mm, and the revs per mile from 780.2 to 766.9. 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, 205/70R15 is +1.7% larger than 215/70R14, which is inside the plus-or-minus 3% guideline. On physical fit, the width change of -10 mm and the rim change from 14 to 15 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.

215/70R14 vs 205/70R15 side by side

Measurement 215/70R14 205/70R15 Difference
Overall diameter 656.6 mm (25.9 in) 668.0 mm (26.3 in) +11.4 mm (+1.7%)
Sidewall height 150.5 mm 143.5 mm -7.0 mm
Circumference 2062.8 mm 2098.6 mm +35.8 mm
Revolutions per mile 780.2 766.9 -13.3
Section width 215 mm 205 mm -10 mm
Rim diameter 14 in 15 in +1 in

Diameter difference between 215/70R14 and 205/70R15: +11.4 mm (+1.7%)

Put the percentage in context. The plus-or-minus 3% guideline exists because small diameter changes produce small speedometer errors, and this change is +1.7%, which is inside that band. In revs per mile the shift is -13.3 (780.2 to 766.9), 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: 215/70R14 to 205/70R15 and back

Going from 215/70R14 to 205/70R15, the diameter grows by +1.7%, so the true speed is the indicated speed multiplied by 1.017. At 30 mph on the dial the car is really doing 30.5 mph; at 50 mph indicated it is 50.9 mph; at 70 mph indicated it is 71.2 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 205/70R15 back to 215/70R14, the error reverses exactly: the ratio becomes 0.983, so 70 mph indicated is really 68.8 mph.

Indicated speed Actual speed fitting 205/70R15 (from 215/70R14) Actual speed fitting 215/70R14 (from 205/70R15)
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: 215/70R14 vs 205/70R15

Sidewall height moves by -7.0 mm between these two sizes (150.5 mm to 143.5 mm), and that is enough to feel. A taller sidewall flexes more, which softens sharp impacts and gives the tyre more give over potholes; a shorter sidewall flexes less, which sharpens the steering response and leaves the rim closer to the road surface on a hard hit. Which of those you get depends on the direction of the change — here the sidewall shrinks — and on the aspect ratio shift from 70% to 70%.

Width, grip and fuel use: 215/70R14 vs 205/70R15

Width changes by -10 mm, from 215 mm to 205 mm. A narrower tyre puts a smaller contact patch on the road, which generally reduces rolling resistance and can help in standing water, but it gives up some dry grip compared with the wider size. 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.

Revolutions per mile and gearing: 215/70R14 vs 205/70R15

The revs-per-mile figures (780.2 for 215/70R14, 766.9 for 205/70R15) describe the gearing effect. 205/70R15 turns -13.3 fewer times per mile, so at any given road speed the engine turns slightly slower with 205/70R15 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 1.7% either way, so the effect on everyday driving is subtle rather than transformative.

Will 205/70R15 clear after 215/70R14? What to check before fitting

Whether 205/70R15 physically fits is a question for your car, not for this table. The numbers say it is taller by 11.4 mm and 10 mm narrower, 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 205 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: 215/70R14 or 205/70R15

The decision comes down to priorities. Comfort follows the sidewall (-7.0 mm here). Grip follows the width (-10 mm here). Instrument accuracy follows the diameter (+1.7% here). Gearing and cruising engine speed follow the revs-per-mile change (-13.3). 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 215/70R14 vs 205/70R15 comparisons and tools

Frequently asked questions

What is the diameter difference between 215/70R14 and 205/70R15?

205/70R15 is +11.4 mm (+1.7%) larger in diameter than 215/70R14: 668.0 mm against 656.6 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 205/70R15 instead of 215/70R14?

On this page, 215/70r14 vs 205/70r15 tyre size comparison is the case in point: The error follows the diameter ratio, +1.7%. 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 205/70R15 wider than 215/70R14, and does that matter?

No — 205/70R15 is 205 mm wide against 215 mm for 215/70R14, 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 205/70R15 fit my car if 215/70R14 fits?

Not necessarily. 205/70R15 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 tyre professional can confirm fitment on your vehicle.

Which size is better, 215/70R14 or 205/70R15?

Neither is better in general — it depends on what you want. 205/70R15 has a -7.0 mm sidewall difference, a -10 mm width difference and a +1.7% 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.