The truck I just bought is completely stock, or at least from what I can tell. If something has been done to the gears, I have no idea. Anyway, the tires on it are 315s, is that too big for a stock? It seems to stutter a bit while accelerating, I don't know if they're causing the problem. Any help is appreciated.

What is the truck?

Blue Goose said:

What is the truck?

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99 F250 Lariat SD ext cab with 5.4L.

In general, 315's are not all that much oversize for an F-250....They do make for a 'taller' final gear ratio. I can't help but to believe your truck has at least a 3:73 gear. If the tag is still on the rear end it will say what the gear is.

Does your truck show any vibration beyond what you described, from a stop? If so it could be a u-joint going bad...

Blue Goose said:

In general, 315's are not all that much oversize for an F-250....They do make for a 'taller' final gear ratio. I can't help but to believe your truck has at least a 3:73 gear. If the tag is still on the rear end it will say what the gear is.

Does your truck show any vibration beyond what you described, from a stop? If so it could be a u-joint going bad...

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From a stop, no. But when it shifts around 50-55MPH, it vibrates quite noticeably.

McCullough said:

From a stop, no. But when it shifts around 50-55MPH, it vibrates quite noticeably.

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I'd venture that there's a balance problem, either with the tires or the drive shaft. Do you feel the vibration in the steering wheel??? If not that should rule out the front tires. Beyond that, can you determine if it's a side to side vibration or a front to rear?

I still wouldn't rule out a bad u-joint though, but I've usually found that those will vibrate at all times.

UTfball68 said:

I'd venture that there's a balance problem, either with the tires or the drive shaft. Do you feel the vibration in the steering wheel??? If not that should rule out the front tires. Beyond that, can you determine if it's a side to side vibration or a front to rear?

I still wouldn't rule out a bad u-joint though, but I've usually found that those will vibrate at all times.

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Driving it today, if I turn off the overdrive, it doesn't shake at 50-55MPH. But if it's on, once it shifts to 5th/OD, it shakes bad until I hit 60MPH.