Tow vehicle with rear tires larger than front tires?

[Cory Lewis]

Looking at a 1985 3/4 ton tow vehicle (originally a gmc crew cab long box, has a recently rebuilt 86 6.2 diesel engine) that has larger tires on the rear wheels than on the front wheels. The larger rear wheels are said to provide better mileage per gallon, although it throws the speedometer off a little.

Will be towing our Biggar which, from descriptions on this board, has a Gross Vehicle maximum of 4,000 lbs.

Seems to me that a trailer on the back may make the higher rear axle a bit of a fulcrum and thereby lessen the weight on the front tires leading to loss of control.

Any merit to this concern? Or should I have paid more attention in science class?

[Darwin Maring]

You would be right if the tong weight was 4000lbs however your hitch weight should be in the couple of hundred pound area. The 4000lb is the tow weight. The larger tires will make the vehicle go faster than the speedometer states. If you have a GPS you can see your exact speed. That heavy truck with that powerhouse engine will pull 4000 lbs like it aint even there.

[Cory Lewis]

Tongue weight. Ah. Thanks.

And thanks for letting me know about the towing ability.

I was wondering whether the truck had been modified for zipping around the city rather than towing long distances. (Don't know how they would park something this big in the city.)

Prior owners have:

Replaced the original 5.7L V8 4BL with a rebuilt 1986 6.2 diesel with a banks turbo kit.

It does have new gauges to tell me what the turbo is doing.

It has a three inch exhaust pipe.

Transmission is now a turbo 400 with a shift kit and a pulling torce torque convertor.

He also replaced the belt system on the front to one that has a single belt rather than two or three.

Disconnected the air conditioner. (Fine by us, we open the windows.)

Am double checking whether it has an intercooler.