1991 is a split year for several Toyota 4Runner brake components. The most useful identification point is the front brake rotor: trucks produced through May 1991 use the earlier rotor dimensions, while June 1991 and later trucks use the thicker later rotor.
Quick answer: which front rotor fits a 1991 Toyota 4Runner?
| 1991 production date | Front rotor diameter | Nominal thickness | Minimum / discard thickness |
|---|---|---|---|
| Through 05/1991 | About 289 mm | 20 mm | 18 mm |
| 06/1991 and later | About 290.5–291 mm | 25 mm | 23 mm |
The small difference in listed outside diameter can vary slightly by manufacturer specification and rounding. The much clearer identifier is the rotor thickness: 20 mm early versus 25 mm late.
How to identify an early or late 1991 4Runner
1. Check the production month
Look for the vehicle production/build month on the Toyota certification label, commonly located in the driver's door-jamb area. A 1991 model produced through May falls on the early side of this brake split; June 1991 and later uses the later application.
2. Measure the existing front rotor
If the vehicle has unknown service history, measure the rotor thickness and compare the dimensions above. This is especially useful on a truck that may have had hub, knuckle, or brake-component swaps.
3. Do not identify the version by outside diameter alone
Early and late rotors are close in diameter. A nominal 289 mm early rotor and roughly 291 mm late rotor can look nearly identical without measurement. Thickness is the easier physical check.
The 1991 split affects more than the rotor
Several front brake applications and wheel-cylinder listings also use the through-05/1991 versus from-06/1991 break. That does not mean every rear brake component follows the same split. Some rear shoes, drums, and hardware are instead separated by standard-duty versus heavy-duty brake configuration. Always read the component-specific fitment notes rather than applying the rotor split to the entire brake system.
Before ordering 1991 4Runner brake parts
- Confirm the production month: through May 1991 or June 1991 and later.
- Confirm 2WD or 4WD when the product listing requires it.
- Measure the existing front rotor thickness if service history is unknown.
- For rear brakes, identify standard-duty versus heavy-duty drum setup where applicable.
- If hubs, knuckles, axles, or brake assemblies were swapped, match the installed hardware rather than the VIN alone.
Relevant brake parts
- Brembo UV Coated OE Front Brake Rotor
- DFC OE Front Brake Rotor
- DFC Front Brake Hardware Kit — 4WD
- DFC Front Brake Hardware Kit — 2WD
If you are uncertain about a 1991 build, use Fitment Help and send the production month plus a rotor-thickness measurement and photos of the installed front brake assembly.
Preserve Rad fitment guides are built from manufacturer application data, dimensional specifications, and our catalog research. Always verify modified vehicles by the components actually installed.