Hi there, everybody...I need some help. I have a '85 short wheelbase F350 4wd. I cut firewood up in the mountains and truck it down to Sydney. Last trip I blew what seems to be the last of any 31x10.50R16.5 tires in Aussie, so I've decided to go bigger--rims and tyres. Does anyone know what modifications are needed for either a 37x12.50R17 or a 38x15.50R17 tyre?

The suspension is stock, I think--three leaves to the front springs, which have a single bolt fixture at the rear and a 120 mm (bolt centre to bolt centre) shackle at the front. There's 45mm of travel between the axle and the bumpstop rubbers.

I'd rather not lift her, because of COG concerns. I'm happy to chop out the fender as much as I need to--I'm mostly concerned as to whether the front wheels will rub on the springs at full lock. Would -25mm offset do the trick? What implications would larger offsets have as to bearing life and steering?

What do you think of the Interco TSL-SSR Super Swamper, especially in the above sizes? Are they likely to wander too much at highway speeds with two ton of firewood on the tray?

Finally, my drivetrain consists of a five litre EFI V8, New Process 435 four speed gearbox, Borg Warner transfer case, and 4.11:1 diffs. Any thoughts on a better combo with the bigger wheels?

 

ok to run that large of tire you would have to do some major cutting and personally would look bad. you could get away with a 4" or 6" with some minor cutting of the fenders and still look nicely. with that size tire they run pretty wide which helps COG as well. also you would benefit from running a 4.56 or 4.88 front/rear gears with that size as well. you have lots of options really at gaining the clearance you need for those tires.

 

Thanks for that, Kemicalburns. I'll look into what's involved with a 4" lift. It's an IFS front end, though, so you'd have to drop the diff case as well, I guess, with that much of a lift. It looks like a serious hassle, all round.

Could you get away with just as much lift as you could manage without major surgery (2"?), and go for a bigger neg offset, like 50mm, to get your clearance at full lock?