195/80R15 vs 205/70R16: Tyre Size Comparison, Diameter Difference & Speedometer Effect

Comparing 195/80R15 with 205/70R16 comes down to four numbers for each size: diameter, sidewall, circumference and revs per mile. 205/70R16 is the taller tyre: its diameter is 693.4 mm against 693.0 mm, +0.4 mm (+0.1%) larger. The width changes by +10 mm (195 mm to 205 mm) and the sidewall by -12.5 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.

Two things decide whether this swap makes sense: the diameter difference and the physical fit. On diameter, 205/70R16 is +0.1% larger than 195/80R15, which is inside the plus-or-minus 3% guideline. On physical fit, the width change of +10 mm and the rim change from 15 to 16 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.

195/80R15 vs 205/70R16 side by side

Measurement 195/80R15 205/70R16 Difference
Overall diameter 693.0 mm (27.3 in) 693.4 mm (27.3 in) +0.4 mm (+0.1%)
Sidewall height 156.0 mm 143.5 mm -12.5 mm
Circumference 2177.1 mm 2178.4 mm +1.3 mm
Revolutions per mile 739.2 738.8 -0.4
Section width 195 mm 205 mm +10 mm
Rim diameter 15 in 16 in +1 in

Diameter difference between 195/80R15 and 205/70R16: +0.4 mm (+0.1%)

A +0.1% diameter change is small enough to sit inside the commonly used plus-or-minus 3% guideline, so the speedometer error it introduces stays modest. The circumference changes by +1.3 mm per revolution, and the revs per mile change by -0.4, which is the same story told from the car's point of view: the instruments count revolutions, so fewer revs per mile means the car travels further per revolution than the instruments assume. That drift also affects the odometer, so recorded mileage moves by the same percentage over time.

Speedometer error: 195/80R15 to 205/70R16 and back

Going from 195/80R15 to 205/70R16, the diameter grows by +0.1%, so the true speed is the indicated speed multiplied by 1.001. At 30 mph on the dial the car is really doing 30.0 mph; at 50 mph indicated it is 50.0 mph; at 70 mph indicated it is 70.0 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 205/70R16 back to 195/80R15, the error reverses exactly: the ratio becomes 0.999, so 70 mph indicated is really 70.0 mph.

Indicated speed Actual speed fitting 205/70R16 (from 195/80R15) Actual speed fitting 195/80R15 (from 205/70R16)
30 mph 30.0 mph 30.0 mph
50 mph 50.0 mph 50.0 mph
70 mph 70.0 mph 70.0 mph

Sidewall height and ride comfort: 195/80R15 vs 205/70R16

Sidewall height moves by -12.5 mm between these two sizes (156.0 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 80% to 70%.

Width, grip and fuel use: 195/80R15 vs 205/70R16

On width, the two sizes are 10 mm apart. The wider tyre (205/70R16) 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: 195/80R15 vs 205/70R16

Gearing follows the circumference. 205/70R16 covers 2178.4 mm per revolution against 2177.1 mm for 195/80R15, so it needs -0.4 fewer revolutions per mile. At a fixed road speed the engine speed drops or rises by the same 0.1% 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 205/70R16 clear after 195/80R15? What to check before fitting

Do not skip the physical check. The diameter difference is +0.1% and the width difference is +10 mm, and both of those affect whether 205/70R16 fits where 195/80R15 did. Check the gap between the tyre 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 tyre 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 205 mm tyre.

Which size suits which priority: 195/80R15 or 205/70R16

The decision comes down to priorities. Comfort follows the sidewall (-12.5 mm here). Grip follows the width (+10 mm here). Instrument accuracy follows the diameter (+0.1% here). Gearing and cruising engine speed follow the revs-per-mile change (-0.4). 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 195/80R15 vs 205/70R16 comparisons and tools

Frequently asked questions

What is the diameter difference between 195/80R15 and 205/70R16?

205/70R16 is +0.4 mm (+0.1%) larger in diameter than 195/80R15: 693.4 mm against 693.0 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 205/70R16 instead of 195/80R15?

Taking 195/80r15 vs 205/70r16 as the case in point: The error follows the diameter ratio, +0.1%. At an indicated 30 mph the true speed would be 30.0 mph, at 50 mph indicated it would be 50.0 mph, and at 70 mph indicated it would be 70.0 mph. The full table in both directions is in the speedometer section above.

Is 205/70R16 wider than 195/80R15, and does that matter?

Yes — 205/70R16 is 205 mm wide against 195 mm for 195/80R15, 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 205/70R16 fit my car if 195/80R15 fits?

Not necessarily. 205/70R16 is taller by 0.4 mm and 10 mm wider, and it needs a 16-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, 195/80R15 or 205/70R16?

Neither is better in general — it depends on what you want. 205/70R16 has a -12.5 mm sidewall difference, a +10 mm width difference and a +0.1% 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.