We really don't know what the final drive ratio will be until he picks out a
tire profile. If it ends up being the 15% difference that he quoted, it will
make it drive like it had 17s and 3.48:1 rear gears. That's pretty close to
the gears that I have. If he were using it for heavy hauling the 4.10s would
be a better choice, but I don't think he'd be putting 22.5s on it then.
That will change my 4.10s into 3.55s or 3.65s. Effectively putting 70MPH at
1800 rpm, which will save a lot of fuel. It will make the ride smoother,
quieter and increase tire life to more than 200k miles. Additionally, it
will add significantly more life to the truck. We are fortunate to have both
the brakes and the suspension to handle the mod. The GM product cannot
without extensive suspension changes. Unfortuately, it also adds 25lbs in
unsprung weight at each wheel, so the shock absorbers should also be changed
to gas type. This change will set me back about $5,000 all in though.
Good question. The answer is "I think so." Let's assume I keep the truck for
200k miles, I will save 3 sets of tires for $1,000 plus say a 10% fuel
savings, which is 11,560 gallons at 17.3 mpg verses 10,526 gallons at 19 mpg
with the difference being 1,000 gal + at say $2.50 a gallon for about
$2,500. So, without the cool factor, the better ride, the better gearing,
the lower stress on the motor and chassis, potentially yes. But, I think the
key to the answer is "How long will I keep the truck?".
You may save tire wear but I'm betting you will use more fuel. Take into
account that the tires and rims are heavier than stock, with the
increased ride height you will have a lot more drag on the road. Plus
those larger tires will take more fuel to get them moving as well as
your ratio change is higher than you have. You will be looking at closer
to a 3.00 ratio. Lower RPM isn't always a good thing. I have never seen
any 22.5 tire that will give a good ride on a light weight vehicle
either. Hope you know a good dentist. If you have ABS your going to have
lot's of fun getting it to work correctly with that much rubber as well.
"Steve Lusardi" < email@example.com> wrote in message
I have done my homework correctly, depending on the tire size, my height
change will be between 3.5 and 6.0 inches. I am running 31s stock. Worst
case is 265/70 at 37", but I will run either 245/70 or 2.55/70 at 34.5 and
36" respectively, which is either a11.3% or 14% gear change. I have 4.10s,
so the effective gear change will be either 3.649 or 3.530. Please remember
that 3.73 is the standard Dodge gear. However, your word of caution will be
heeded because both the wheels and tires in that size are not always round
and any imbalance or eccentricity will get my undivided attention. On the
fuel issue, I have queried others that have made this change and the fuel
savings is substantial. Their stated change in consumption is far greater
than I'm planning on. In actual fact, the rolling resistance is less with
the big wheels as the tire width is only slightly wider than stock, but with
a much harder compound.
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