Gear ratio =?
Logistics Pro
Joined: Aug 2003
Posts: 4,701
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Generally, the lower ratio gives more torque feeling for towing. As far as mileage, it is tricky because it is dependent on more than just the ratio. Tire size, tranny ratio, and optimal engine torque range can affect the mileage. Usually, a little higher ratio (smaller number) gives better mileage, but this is not always the case. In your example, generally the 3.55s will do better for towing, and the 3.08s will be better for mileage since they drop the rpms on the highway. Hope this helps, Ted
Postmaster
Joined: Dec 2002
Posts: 3,959
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From: USA
I'll add a little to the good info that Ted gave.
In a light weight truck, a high (numerically low) ratio can give good mileage when unloaded. In a heavy truck, or a light truck used for towing, a high ratio (numerically low, such as 3.08) usually gives poor mileage and poor towing performance. If the truck has an overdrive tranmission, it's usually better to get the lower axle ratio (such as 4.10) if you intend to tow with the truck, or if the truck is heavy when empty (like a crewcab 1-ton), as the low ratio gives good towing performace and good mileage when towing, and the overdrive ratio allows for better mileage when unloaded or at higher speeds on the freeway. In a half-ton truck, 3.55 is usually a good ratio unless you're towing alot. In a 3/4-ton or 1-ton, go for the 3.73 or 4.10 ratio. 3.08 is really only good for a half-ton that will never see towing duty or large tires.
Half-ton truck's gearing usually starts at 3.08 and goes down to 3.55. 3/4-ton and 1-ton truck's gearing usually starts at 3.55 and goes down to 4.10. I run 4.56's in my 1-ton because of the heavy truck, small engine and large tires.
In all trucks, a bigger engine can pull higher gears and typically a smaller engine needs lower gears to get it up into it's powerband. Larger tires also demand lower gears. Diesels and inline-sixes can usually get away with higher gears, since they produce their power at such low rpm's.
In a light weight truck, a high (numerically low) ratio can give good mileage when unloaded. In a heavy truck, or a light truck used for towing, a high ratio (numerically low, such as 3.08) usually gives poor mileage and poor towing performance. If the truck has an overdrive tranmission, it's usually better to get the lower axle ratio (such as 4.10) if you intend to tow with the truck, or if the truck is heavy when empty (like a crewcab 1-ton), as the low ratio gives good towing performace and good mileage when towing, and the overdrive ratio allows for better mileage when unloaded or at higher speeds on the freeway. In a half-ton truck, 3.55 is usually a good ratio unless you're towing alot. In a 3/4-ton or 1-ton, go for the 3.73 or 4.10 ratio. 3.08 is really only good for a half-ton that will never see towing duty or large tires.
Half-ton truck's gearing usually starts at 3.08 and goes down to 3.55. 3/4-ton and 1-ton truck's gearing usually starts at 3.55 and goes down to 4.10. I run 4.56's in my 1-ton because of the heavy truck, small engine and large tires.
In all trucks, a bigger engine can pull higher gears and typically a smaller engine needs lower gears to get it up into it's powerband. Larger tires also demand lower gears. Diesels and inline-sixes can usually get away with higher gears, since they produce their power at such low rpm's.
Last edited by SoCalDesertRider; Aug 20, 2004 at 11:37 PM.
