Audi Tire Size Guide

How to Read an Audi Tire Size

Every Audi tire has a size code molded into the sidewall. It is a string of numbers and letters, and each part gives one piece of information. The same size and load index are printed on the tire pressure label on the driver's B-pillar.

A typical Audi Q5 rear sidewall might read: 235/55 R19 101H, a size Audi lists for the Q5. Here is what every part means:

Why Overall Diameter Is the Number That Actually Matters

Width and aspect ratio are the two numbers you see first, but the figure that sets speedometer accuracy, rolling circumference, wheel arch clearance and effective gearing is the overall diameter. That is the width × aspect ratio × 2 (for both sidewalls) plus the rim diameter, all converted to inches:

Audi's owner's manuals ask for tires with the same design, size (rolling circumference) and as close to the same tread pattern as possible on all four wheels. Continental advises keeping rolling circumference within 3% of the original; Audi publishes no percentage in the manuals we checked. Use our Audi tire calculator to check any new size against your stock diameter instantly. For the percentage between any two sizes, the tire size difference calculator does it, and what other makers say about mixing sizes is in the AWD tire size mismatch guide.

How to Choose an Audi AO Tire

We do not rank tire brands on this page. We could not source a ranking from Audi, and star ratings from owner forums are not data we can verify. What Audi does say is that it recommends Audi Original Tires, that Audi Tire Centers sell tires from leading tire manufacturers designed to fit and perform with your specific Audi, and that tire performance can differ even in the same size.

How to choose

• Match the marking on your current tires. Look for AO, R0 or RE0 on the sidewall and choose the same type.
• Match size, load index and speed rating. Use the tables on this page and the tire pressure label on your car.
• Change in pairs at minimum. Audi says not to replace tires individually, and on all-wheel-drive cars to keep the same brand, construction and tread pattern on all four wheels.
• Ask an Audi Tire Center or dealer. Audi USA offers a tire concierge line for choosing tires for your car.

Audi EV Tire Sizes and the Load Index

Audi's owner's manuals list a load index for every factory size, and Audi says to check the tire sidewall for the designated load rating of a specific tire. On the electric models the sizes are often staggered, with a wider rear, and the rear tire has its own load index. A replacement tire with the same size code but a lower load index than the one you are replacing is not equivalent, even if it fits the rim.

Always read the load index on your current tires and the tire pressure label, and never accept a lower figure because the price is better.

Choosing Replacement Tires for Audi EVs

• Check the marking: Audi USA identifies Audi Original Tires by R0, RE0 and similar sidewall markings.
• Check the load index of each axle: staggered cars list a different load index for the rear tires.
• Replace in pairs at minimum: Audi says not to replace tires individually.

Plus Sizing Your Audi: The Right Way to Do It

Plus sizing, fitting a larger-diameter wheel with a lower-profile tire to keep the same overall diameter, is a popular Audi upgrade. Audi's manual says to consult an authorized Audi dealer before fitting a tire and rim combination different from the factory one, and not to choose tires on nominal size alone because tires of different construction can differ greatly even in the same size.

Audi publishes no percentage. Continental advises keeping rolling circumference within 3% of the original, so keep the new diameter as close to stock as you can.

A Step-by-Step Audi A4 Plus-Sizing Example

Stock fitment: 225/50 R17 (overall diameter 25.86"). The next two sizes are the A4 18 and 19 inch sizes in the owner's manual.

Plus Sizing Checklist for Audi Owners

• Calculate the new diameter first. Use our calculator before ordering anything.
• Check clearance. Audi says to make sure the tires have enough clearance to the vehicle, because tires of different construction can differ greatly even in the same size.
• Keep the load index and speed rating. Check the sidewall for the designated load rating, as Audi advises.
• Use approved combinations. Audi says to use only tire and rim combinations and wheel bolts approved by Audi.
• Ask a dealer. Audi says to consult an authorized Audi dealer before fitting a combination different from the factory one.

Staggered Fitment on Audi: When It Applies

Most of the combustion models in Audi's USA manuals list the same size on the front and rear. The electric models and the R8 list a different, wider rear size on most wheels:

• Audi e-tron GT / RS e-tron GT: 245/45 R20 front and 285/40 R20 rear (a 1.0% diameter difference, calculated); 265/35 R21 front and 305/30 R21 rear; and 225/55 R19 front with 275/45 R19 rear on the e-tron GT.
• Audi R8 Coupe / Spyder: 245/35 ZR19 front with 295/35 ZR19 rear, or 245/30 ZR20 front with 305/30 ZR20 rear. The rear tire is about 5.4% to 5.5% larger in diameter than the front (calculated), a much bigger gap than the electric models.
• Audi Q4 e-tron: 235/55 R19 front with 255/50 R19 rear, and 235/50 R20 front with 255/45 R20 rear (about 0.5% and 0.7% apart in diameter, calculated).
• Audi Q6 / SQ6 e-tron: every wheel size has a wider rear, for example 235/60 R19 front with 255/55 R19 rear and 255/50 R20 front with 285/45 R20 rear (each within about 0.2% in diameter, calculated).

Where front and rear sizes differ they cannot be swapped between axles. Audi's manual describes tire rotation as installing the tires from the rear axle on the front and vice versa, so on a staggered car ask your dealer how to rotate.

If upgrading wheels on either model, use our Staggered Fitment Calculator to compare front and rear diameters, and the wheel offset and backspacing converter for the wheels themselves.

Run-Flat Tires on Audi

Audi USA mentions all-season run-flat tires on the Q5 and SQ5, and Audi's manual describes run-flat tires as having reinforced sidewalls that let you keep driving after a loss of pressure. The manual says run-flat tires may only be used on vehicles that were equipped with them at the factory, that they must be installed on all four wheels, and that mixing tire types is not permitted. If you have to drive with too little pressure, Audi says not to drive faster than 50 mph (80 km/h). Ask an Audi dealer before changing tire type.

RS and S-Model Tire Sizes

Audi's S models list lower-profile tires than the standard cars in the owner's manuals. The A4 sedan lists 225/50 R17, 245/40 R18 and 245/35 R19, while the S4 lists 245/40 R18 and 255/35 R19. The lower the aspect ratio, the shorter the sidewall: 255/35 R19 has a sidewall of about 3.5 in (calculated), against 4.4 in for 225/50 R17. Audi says tires should not be chosen on nominal size alone because tires with a different construction can differ greatly even in the same size.

Audi's manual says winter tires must be approved for your vehicle and fitted on all four wheels, so ask your dealer which winter size is approved for your S or RS model rather than choosing one yourself.

5 Common Audi Tire Mistakes

1. Replacing only the punctured tire on an all-wheel-drive Audi. Audi says not to replace tires individually; at least replace both tires on the same axle, and keep the same brand, construction and tread pattern on all four wheels.
2. Inflating to the tire sidewall maximum. The pressure label on the B-pillar is your target, not the sidewall figure.
3. Choosing a size on the nominal size alone. Audi says tires of different construction can differ greatly even in the same size, so check clearance and ask a dealer.
4. Running summer tires in winter and expecting quattro to compensate. Audi says summer tires provide less traction on ice and snow.
5. Fitting a lower load index than the original. Audi says to check the sidewall for the designated load rating of a specific tire.