Can 3.73 gears run 35-inch tires?

Yes—3.73 gears can turn 35-inch tires and many trucks and Jeeps drive acceptably with this combo, especially on flat roads and without heavy towing. However, expect softer acceleration, more frequent downshifts, lazier crawl performance off-road, and possible fuel economy and transmission-temperature penalties. For best all-around performance, many owners regear to somewhere between 4.10 and 4.88 depending on engine, transmission, vehicle weight, terrain, and how the vehicle is used.

What actually changes when you move to 35s on 3.73s

Upsizing to 35-inch tires effectively “tallens” your gearing. That reduces torque at the wheels and lowers engine RPM for a given road speed in top gear. The result can be slower takeoff, more downshifting on grades, earlier converter lock/unlock activity in automatics, and a weaker crawl ratio off-road. Modern 8–10-speed transmissions can mask some of this with closer steps and deep first gears, but the physics remain.

Highway RPM, by the numbers

Engine speed at cruise helps illustrate the feel. Using the common formula RPM ≈ (MPH × top-gear ratio × axle ratio × 336) ÷ tire diameter, 65 mph with 35-inch tires yields roughly:

– With 3.73s and a 0.67 top gear (typical 8-speed): about 1,560 RPM
– With 3.73s and a 0.75 top gear (older 4–6 speeds): about 1,740 RPM
– With 4.56s and a 0.67 top gear: about 1,900 RPM
– With 4.56s and a 0.75 top gear: about 2,140 RPM

Most naturally aspirated gas engines feel happier and downshift less when cruising near 1,900–2,200 RPM at 65–70 mph. Turbocharged gas and diesel engines tolerate lower cruise RPM better, but the heavier 35s still sap acceleration.

What determines if 3.73s with 35s are “good enough”

Whether you’ll be content with 3.73s on 35s depends on a mix of hardware and how you use the vehicle. The points below clarify the key variables that shape drivability and durability.

• Engine torque curve: High low-end torque (turbo gas or diesel) masks tall gearing better than peaky naturally aspirated engines.
• Transmission: More ratios (8–10 speeds) and a deep first gear help launches and reduce hunting compared to older 4–6 speeds.
• Vehicle weight and aero: Heavier, boxier rigs feel the gearing penalty more than lighter, slippery ones.
• Terrain and altitude: Hills, headwinds, and high elevation expose tall gearing; expect frequent downshifts.
• Use case: Towing, hauling, or rock-crawling benefit from shorter (numerically higher) gears; light commuting on flat ground is more forgiving.
• Tire reality: Many “35s” measure 34–34.5 inches. Slightly smaller true diameter raises RPM a bit, partially offsetting the gearing hit.

Taken together, these factors explain why some owners report “it’s fine,” while others find 3.73/35s frustrating. The same ratio-tire combo can feel very different across vehicles and routes.

Suggested axle ratios for 35-inch tires

The following guidelines reflect common setups and owner experience across modern trucks and Jeeps. Exact needs vary with engine, transmission, and intended use.

• Modern 8–10-speed gas half-tons (F-150, Silverado 1500, Ram 1500): 3.73 is workable for daily driving on flat ground. If you tow, live in hilly terrain, or want snappier feel, 4.10–4.30 is a sweet spot.
• Older 4–6-speed autos or manuals (including many pre-2015 half-tons): 4.56 typically restores stock-like performance with 35s; 4.88 if you prioritize response or off-road.
• Jeep Wrangler/Gladiator (gas): Driveable on 3.73 with 35s, but 4.56–4.88 is widely favored for mixed on/off-road use and better crawl. Manuals lean toward 4.88.
• Toyota Tacoma/4Runner (3.5L): 3.73/35s feel undergeared; 4.88–5.29 is commonly recommended to curb hunting and improve crawl.
• Diesel pickups/SUVs: 3.31–3.73 often acceptable on 35s thanks to abundant low-end torque; 4.10 if towing heavy or in steep terrain.
• Rock-crawling focus: 4.88–5.13 with 35s to regain crawl ratio and reduce clutch/transmission strain.

Use your transmission’s top gear and your tire’s true diameter to target a cruise RPM that suits your engine. Local terrain and towing habits should nudge you up or down within these ranges.

If you keep 3.73s: how to make it livable

Plenty of owners stay on 3.73s with 35s. These steps help preserve drivability, protect the transmission, and keep costs in check.

1. Recalibrate the speedometer and, if possible, transmission shift schedule for the new tire size.
2. Run appropriate tire pressures and choose lighter wheels/tires to reduce rotational mass.
3. Use Tow/Haul mode or lock out top gear on grades to cut hunting and heat buildup.
4. Consider a conservative engine/transmission tune or throttle mapping to sharpen response.
5. Monitor transmission temps; an auxiliary cooler can be smart in hot climates or when towing.
6. Expect more frequent downshifts and potentially a small fuel economy penalty versus stock-size tires.

These measures won’t change the fundamental gearing, but they can meaningfully improve everyday manners and longevity.

When you should strongly consider regearing

Regearing isn’t cheap, but it can transform how a 35-inch setup drives. If the scenarios below sound familiar, shorter gears are likely worth it.

• Regular towing over roughly 3,500–5,000 pounds or frequent mountain driving
• Manual transmission needing excessive clutch slip on hills or off-road
• Rock-crawling where control and low-speed torque are priorities
• Constant gear hunting, sluggish throttle response, or excessive trans temps
• Desire to return cruise RPM to the engine’s efficient torque band

For many gas engines, targeting about 1,900–2,200 RPM at 65–70 mph balances response and efficiency. Regearing also restores crawl ratio, easing strain on clutches, transmissions, and axles when off-road.

Costs, parts, and other considerations

Expect roughly $1,200–$2,500 per axle installed for quality gears, bearings, and setup in North America; labor and parts quality drive variance. A 4×4 typically needs both front and rear axles matched. Plan for break-in (gentle driving and gear oil change after the initial few hundred miles), speedometer recalibration, and, if desired, lockers or limited-slip units during the same service. Bigger tires also add stress—upgraded axle shafts, ball joints, brakes, and steering components may be prudent depending on vehicle and use.

Summary

3.73 gears will run 35-inch tires, and many modern vehicles remain serviceable for light-duty use. If you want stronger acceleration, less downshifting, better crawling, or tow and drive in hills, regearing is the proven cure: think 4.10–4.30 for many 8–10-speed half-tons, 4.56–4.88 for Jeeps and older 4–6-speed trucks, and even deeper for Tacoma/4Runner builds or rock-crawling. Calibrations, smart driving, and heat management help if you keep 3.73s, but gearing remains the most effective fix.