What Lift?
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Joined: Aug 2004
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From: Michigan
What Lift?
I have a lift size question. I have an 88 F150 that I will be puting 33's and a 3" body lift on in the next couple of weeks. Down the road a little I would like to add a suspension lift and 35's. I know the lift law in Michigan is 24" to the frame and 26" to the bumper. What is the highest lift that I can put on it to keep it as close to legal as possible just in case it is ever checked? I know that the body lift will only affect the bumper height but I am working on a custom one that will fill the gap and keep it low. I would like to go with the 6" lift just because.
Also if anyone has any idea of the best gearing to run in that truck. Currently I am running a stock 3:08 with 31's and it is a slight dog on take off. I know that it will only get worse with the bigger tires. It has a 5-speed 300 6 that gets awfull mileage and I know that will get worse too. But hey if I wanted milage I would buy a yugo. Speaking of which I was passed on take off by one the other day
. HELP!
Frank
Also if anyone has any idea of the best gearing to run in that truck. Currently I am running a stock 3:08 with 31's and it is a slight dog on take off. I know that it will only get worse with the bigger tires. It has a 5-speed 300 6 that gets awfull mileage and I know that will get worse too. But hey if I wanted milage I would buy a yugo. Speaking of which I was passed on take off by one the other day
. HELP!Frank
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Joined: Mar 2004
Posts: 1,321
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From: MI
here some useful you can use to answer that.
Below are some of the mathematical formulas used to answer commonly asked questions concerning fitments of light truck tires.
"How much extra ground clearance under the axles will be provided?" or "How much will it raise the vehicle's center of gravity?"
(New Tire Diameter-Original Tire Diameter) / 2 = Approx. change in ground clearance and center of gravity
Example:
(32.5" - 27") / 2 = 2.75" change (increase) in ground clearance and center of gravity
"How will it affect the acceleration performance of the truck?"
The answer is that it has the same affect as changing the axle ratio of the truck.
(Original Tire Diameter / New Tire Diameter) X Original Axle Ratio = Effective Axle Ratio
Example:
(27" / 32.5") X 3.50 Original Axle Ratio = 2.91 Effective Axle Ratio
"How will it affect the performance of the truck on the highway?"
(Original Tire Diameter / New Tire Diameter) X RPM@MPH = New RPM @ actual MPH
This example is for 55 MPH
Example:
(27" / 32.5") x 2400 RPM = 1985 RPM @ 55 mph with new tires.
"How far off will the speedometer be?"
May be speeding ticket time!
(New Tire Diameter / Original Tire Diameter) X Indicated Speed = Actual Speed with new tires
Example:
(32.5" / 27") X 55MPH = 66.2 MPH Actual Speed with new tires
"What can I do to regain the performance?"
Change the differential gears if the truck is equipped with solid axles at a cost of about $400 - $500 per axle.
(New Tire Diameter / Original Tire Diameter) X Original Axle Ratio = Required Axle Ratio
Example:
(32.5" / 27") X 3.50 Original Axle Ratio = 4.20 Required Axle Ratio
Below are some of the mathematical formulas used to answer commonly asked questions concerning fitments of light truck tires.
"How much extra ground clearance under the axles will be provided?" or "How much will it raise the vehicle's center of gravity?"
(New Tire Diameter-Original Tire Diameter) / 2 = Approx. change in ground clearance and center of gravity
Example:
(32.5" - 27") / 2 = 2.75" change (increase) in ground clearance and center of gravity
"How will it affect the acceleration performance of the truck?"
The answer is that it has the same affect as changing the axle ratio of the truck.
(Original Tire Diameter / New Tire Diameter) X Original Axle Ratio = Effective Axle Ratio
Example:
(27" / 32.5") X 3.50 Original Axle Ratio = 2.91 Effective Axle Ratio
"How will it affect the performance of the truck on the highway?"
(Original Tire Diameter / New Tire Diameter) X RPM@MPH = New RPM @ actual MPH
This example is for 55 MPH
Example:
(27" / 32.5") x 2400 RPM = 1985 RPM @ 55 mph with new tires.
"How far off will the speedometer be?"
May be speeding ticket time!
(New Tire Diameter / Original Tire Diameter) X Indicated Speed = Actual Speed with new tires
Example:
(32.5" / 27") X 55MPH = 66.2 MPH Actual Speed with new tires
"What can I do to regain the performance?"
Change the differential gears if the truck is equipped with solid axles at a cost of about $400 - $500 per axle.
(New Tire Diameter / Original Tire Diameter) X Original Axle Ratio = Required Axle Ratio
Example:
(32.5" / 27") X 3.50 Original Axle Ratio = 4.20 Required Axle Ratio
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