Chevrolet Tahoe 5th gen: the sidewall cost of 22-inch wheels

Three fitments, and the sidewall is the variable

265/70R17 at 31.61 in carries 7.30 in of sidewall. 275/60R20 at 32.99 in carries 6.50 in. 275/50R22 at 32.83 in carries 5.41 in.

The diameters span 1.39 in — 4.38% from the shortest to the tallest — while the sidewall falls by nearly two inches across the same range. On a vehicle designed to carry seven or eight people and their luggage over whatever surface is between here and the destination, that is the trade the trim ladder is actually making.

The 20-inch fitment is the tallest of the three, marginally above the 22. Larger wheel, shorter tire, again.

The sizes owners move to

• 285/70R17 at 32.71 in — from the 17-inch fitment, +1.10 in and 3.49%.
• 33x12.50R20 at 33.00 in — from the 22-inch fitment, +0.17 in and 0.53%; from the 17-inch fitment, +1.39 in and 4.41%.
• 285/65R20 at 34.59 in — from the 20-inch fitment, +1.59 in and 4.83%; from the 17-inch fitment, +2.98 in and 9.43%.

Only that last figure is a large change. Everything else on this platform is under 5%, which is what you would expect on an independent-suspension SUV with limited room in its wheel wells and a ride quality brief.

Moving off the 22s

For an owner on 275/50R22, the interesting numbers are not the height figures at all. Fitting 33x12.50R20 changes rolling diameter by 0.53% — nothing — while adding 1.67 in of section width and, crucially, moving from 5.41 in of sidewall to 6.50 in.

Going further, to 285/65R20, adds 5.36% of height and takes the sidewall to 7.29 in: nearly two inches more than the 22-inch package, on a wheel two inches smaller.

That is the whole argument for the swap. The tire gets taller almost incidentally; what the owner is buying is the cushion between the rim flange and a pothole, and a much wider choice of tire models than 22-inch fitments offer.

The load side of a family vehicle

A three-row SUV at capacity is a heavily loaded vehicle, and the placard pressures were chosen against the original tire's load and inflation curve. A substitution changes which curve applies, and the pressure that carries the same load can be different even when the size looks similar.

That is not visible in any figure this site computes, all of which is geometry. Pressure and load tables covers how the comparison is actually made.

The gearing question, on a platform where it is quiet

Given that the largest recorded change here is 9.43% and most are half that, the gearing consequence is modest in every case — a multi-ratio automatic responds to a 4% change by shifting slightly differently rather than by running out of range.

Where you want the exact engine-speed figure, the gear ratio calculator takes the ratio from your own vehicle.

The spare is a different tire

Full-size SUVs of this class carry a spare that is frequently neither the same size nor the same construction as the four on the ground, and it lives under the vehicle where nobody looks at it. After a size change it is the odd one out by whatever the change was — a 9.43% mismatch in the case of the largest step here.

On a vehicle with an automatic four-wheel-drive mode, a spare of a materially different rolling circumference is a difference the driveline has to absorb rather than ignore. It is worth knowing the number before the day you need the tire, and the number is exactly the percentage figures above.

Geometry, and then the wheel well

None of the above says a tire clears. This generation moved the rear axle to independent suspension, which changed what sits close to the rear tire without changing anything at all about the size code — and at the front, the liner, the sway bar link and steering travel still decide contact. Two trims of the same year with different wheel offsets do not have the same room.