35's on 90 F250?
#1
35's on 90 F250?
I have a gas 1990 F250 4WD and I need new tires and want to put a set of 35 inch or 315/75R tires on it. I would buy a 4 or 6 inch lift but I already have a set of new Rancho RS900X's. Rancho said I can put up to a 2 inch lift and use the same shocks, they might have said 2 inches for warranty issues and it would be ok to go a little higher, but I dont know. Can I run These tires with a leveling kit and/or a body lift? Could I add leafs or put blocks in? Thanks
#2
You can put taller blocks in the rear, but not the front. Never put blocks in the front. Don't stack blocks on top of one another either, just use one block of the correct height. F350 factory rear blocks are about 2" taller than F250 factory blocks, so that is one avenue open to you if you just want a 2" lift for the rear.
Another choice is add-a-leafs under the stock springs. This can be done both front and back. The ride will be stiffer with the add-a-leaf. On the front, you can have your stock springs re-arched, or go with a new set of lift springs, or use F350 springs if you just want a 2" lift in the front.
Yes, you should be able to use the Ranchos with a 2" lift. Rancho lists the same part number for F250 and F350 rear shocks even though the F350 is 2" taller in the back than the F250.
You should be able to put 35's on it with a 2" lift. They might rub when 4 wheeling though. A 4" lift would be better if you intend to flex out the suspension offroad. You will likely need to shim the front bumper forward an inch or so to keep the tires from rubbing the lower corners when turned. Or you can trim some metal off the lower corner of the bumper if you dont want to shim it.
On my F350 4x4, I run 33x12.50's with the stock suspension and shimmed the bumper forward. I get no rubbing at all when off road or when turning.
When going with the taller tires, also consider that your effective axle ratio changes as a result of the larger tire diameter. Depending on what engine is in the truck, if you have 3.55 gears in the truck, I don't advise going with 35" tires, too much power loss, not enough torque multiplication at the axle. If you have 4.10's and don't use the truck for towing, you'll probably be ok with the 35's. If you want to tow with it, a change to 4.56's gears will help out alot with power for climbing grades with the extra trailer weight and taller tires.
A good compromise on tire size is 33x12.50's. They look beefy on the truck, are big enough for most general off roading, and aren't too much taller than the stock tires so they don't have as great a negative effect on the gearing and don't throw off the speedo as much either. You may not have to lift the truck to run 33's either, so you could save some money not having to mess with the suspension.
Anyways, just a thought. Good luck with the truck!
Another choice is add-a-leafs under the stock springs. This can be done both front and back. The ride will be stiffer with the add-a-leaf. On the front, you can have your stock springs re-arched, or go with a new set of lift springs, or use F350 springs if you just want a 2" lift in the front.
Yes, you should be able to use the Ranchos with a 2" lift. Rancho lists the same part number for F250 and F350 rear shocks even though the F350 is 2" taller in the back than the F250.
You should be able to put 35's on it with a 2" lift. They might rub when 4 wheeling though. A 4" lift would be better if you intend to flex out the suspension offroad. You will likely need to shim the front bumper forward an inch or so to keep the tires from rubbing the lower corners when turned. Or you can trim some metal off the lower corner of the bumper if you dont want to shim it.
On my F350 4x4, I run 33x12.50's with the stock suspension and shimmed the bumper forward. I get no rubbing at all when off road or when turning.
When going with the taller tires, also consider that your effective axle ratio changes as a result of the larger tire diameter. Depending on what engine is in the truck, if you have 3.55 gears in the truck, I don't advise going with 35" tires, too much power loss, not enough torque multiplication at the axle. If you have 4.10's and don't use the truck for towing, you'll probably be ok with the 35's. If you want to tow with it, a change to 4.56's gears will help out alot with power for climbing grades with the extra trailer weight and taller tires.
A good compromise on tire size is 33x12.50's. They look beefy on the truck, are big enough for most general off roading, and aren't too much taller than the stock tires so they don't have as great a negative effect on the gearing and don't throw off the speedo as much either. You may not have to lift the truck to run 33's either, so you could save some money not having to mess with the suspension.
Anyways, just a thought. Good luck with the truck!
Last edited by SoCalDesertRider; 01-24-2005 at 09:09 PM.
#4
I didnt know if it was ok to run a body lift or not. I have heard that it is really hard on those long bolts when you have a 3/4 ton truck. 2 inches in leafs and blocks, and then maybe a 2 inch body lift sounds good. When you respring the leafs does that make the ride a little softer? I will find out about the gearing too. Thanks.
#5
Personally, I stay away from body lifts after having a truck with a 3" body lift. Some people like them but on my old truck, the sheetmetal was all cracked around body lift blocks and the bed floor was wavy. It was a 3/4 ton truck that had been used hard. I don't know how many years the body lift was on it. The bodies seem to last longer when they are supported the way they were intended to be on the factory mounts.
As for re-springing making the ride harder or softer, that depends on the kind of springs you use. Ask about the spring rate and compare to your existing spring rate.
As for re-springing making the ride harder or softer, that depends on the kind of springs you use. Ask about the spring rate and compare to your existing spring rate.
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