What is the rear diff ratio of the IS250?
Most Lexus IS250s use a 3.27:1 rear final-drive ratio in stock rear-wheel-drive configurations; however, the exact ratio can vary by model year, market, and drivetrain (RWD vs AWD).
Drivetrain variations and typical ratios
The IS250 was offered in both rear-wheel drive (RWD) and all-wheel drive (AWD) across different markets. Here are the commonly observed final-drive figures by configuration.
- IS250 RWD (most North American models): 3.27:1 final drive
- IS250 AWD: commonly the same rear ratio (3.27:1) but some markets or years may have different rear-axle gearing; verify for your specific vehicle
In practice, most IS250 owners will find the rear differential geared for a balance between highway efficiency and performance, with the RWD version typically aligning with the 3.27:1 figure. Always confirm with your vehicle’s official documentation or hardware tags, since regional production changes can occur.
How to verify the exact ratio on your IS250
Because the final-drive can vary by year and market, the most reliable way to know your specific ratio is to check official labels, documentation, or a VIN-based specification lookup. The following methods can help identify the precise figure for your car.
- Inspect the differential housing tag for a stamped “FD” (final drive) or a direct 3.27:1, 3.21, etc., indicator.
- Consult the vehicle’s owner’s manual or service manual; drivetrain specifications sometimes list the final-drive ratio by model and year.
- Use the VIN to pull the specs from a Lexus/Toyota service system or parts database (many dealers can provide the exact final-drive ratio for your VIN).
- If you must measure manually, work with a qualified technician: you can determine the ratio by counting gear teeth on the ring gear and pinion or by measuring driveshaft revolutions per wheel turn, but this requires proper tools and safety precautions.
Confirming the exact ratio is important for maintenance, gear swaps, or performance tuning, so rely on official sources or a trained technician when in doubt.
Summary
In summary, the IS250’s rear differential is typically geared around 3.27:1 for most RWD configurations, with AWD models often sharing the same rear ratio but subject to year- and market-specific variations. To ensure accuracy for a specific vehicle, consult the differential tag, the owner or service manual, or a Lexus dealer using the VIN. Understanding the exact final-drive ratio helps with maintenance decisions, part compatibility, and performance planning.
