the right size
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Freshman User
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the right size
I have a 1991 ford f 250
I't has a c6 auto with a 308 diff ratio my tyre size was 275 70 16" rims
the truck used to run well on the highway
and when sitting on a speed of 60mph the motor would only rev
around 2100 or 2200 rpm
this was fine intill I towed my small boat , I could travel over 50 mph I had no
pull at all the more a put my foot down my petrol gauge went down it was
bad I had to sit on a slow speed.
The boat and trailor approx weight 370kg
somebody told me I should change my tyre size cause there to big and go back to standard,
any other ideas?
I't has a c6 auto with a 308 diff ratio my tyre size was 275 70 16" rims
the truck used to run well on the highway
and when sitting on a speed of 60mph the motor would only rev
around 2100 or 2200 rpm
this was fine intill I towed my small boat , I could travel over 50 mph I had no
pull at all the more a put my foot down my petrol gauge went down it was
bad I had to sit on a slow speed.
The boat and trailor approx weight 370kg
somebody told me I should change my tyre size cause there to big and go back to standard,
any other ideas?
Postmaster
Joined: Dec 2002
Posts: 3,959
Likes: 9
From: USA
275/70-16 is an odd-ball size. If they are actually that size, the tires are about 31" tall, which is a little shorter than the stock tire size (235/85-16, about 31.5" tall).
I don't know how much 370 Kg is in American lbs, so i can't say anything about that subject.
I will say the thing that's most likely killing your towing power is the high (numerically low) axle ratio (3.08). That is not a ratio known for good towing power and is also the reason why your engine rpms are so low. I don't know what engine you have in the truck, but most gas engines pull better between 2500 to 3000 rpm at cruise speed. Down around the low 2000's at cruise is like being in overdrive all the time, which your C6 tranmission doesn't have.
Gear it down to 3.73 or 4.10 and you will get alot more pulling power out of that truck and probably get better mileage when towing too, since the engine won't have to spend so much time at wide open throttle operating below it's optimum powerband.
I don't know how much 370 Kg is in American lbs, so i can't say anything about that subject.
I will say the thing that's most likely killing your towing power is the high (numerically low) axle ratio (3.08). That is not a ratio known for good towing power and is also the reason why your engine rpms are so low. I don't know what engine you have in the truck, but most gas engines pull better between 2500 to 3000 rpm at cruise speed. Down around the low 2000's at cruise is like being in overdrive all the time, which your C6 tranmission doesn't have.
Gear it down to 3.73 or 4.10 and you will get alot more pulling power out of that truck and probably get better mileage when towing too, since the engine won't have to spend so much time at wide open throttle operating below it's optimum powerband.
Thread Starter
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Freshman User
Joined: Dec 2004
Posts: 32
Likes: 0
THANKS FOR YOUR REPLY
the engine is a 351w efi
the tyre standard tyre size in my owners manual say's
LT225/75 r16
does LT MEAN ANYTHING
the engine is a 351w efi
the tyre standard tyre size in my owners manual say's
LT225/75 r16
does LT MEAN ANYTHING
Last edited by yabbieboy; Feb 1, 2005 at 08:22 AM. Reason: add on
