I’ve always wondered how much stopping distance is given up when an owner jacks up his halfton pickup and puts huge knobby rock crawling tires on it.
I especially wondered this morning when I was tailgated by such a monstrosity at 45 mph in traffic on I-5. I pulled over as soon as I noticed it.
Also, on a previous trip, I was passed by a very large 4 door F350. Not only was it an extremely large vehicle (normal tires however) but on the rear, outside the tailgate, was a platform bearing a full size Harley Davidson parallel to the truck’s bumper.
What, do you suppose, would happen in a sudden evasive maneuver at speed?
I don’t believe that either of these vehicle configurations would be allowed on the road in Europe.
If the vehicle was upgraded with better brakes to compensate for the added weight of the larger wheels and tires, the only other significant issue would be a higher center of gravity. Suffice it to say handling will not improve as ride height rises.
It really depends on how well the modification is done. If done correctly, it can handle better than it did in it’s stock configuration. Of course the laws of physics must be considered to determine what needs to be done to the suspension, brakes, and tires.
Loading a rig incorrectly is a separate issue and should be adressed as such.
No matter how well the engineering for the modifications are, If the rig is opperated beyond it’s specifications, it will not preform well.
In terms of straightline braking performance, the bigger tires should actually improve things. The biggest factor in stopping distance for modern cars is traction, which all things being equal the bigger contact patch on the bigger tires should help. Bigger tires and wheels add weight, but not that much. Knobbies are going to be a lot worse on pavement than a highway tread tire, but all things being equal bigger tires are better.
Keep in mind that these are usually pretty heavy duty trucks in their stock form. They’re designed to haul many, many tons and have ginormous brakes that are up to the task. Most of the big lifted ones aren’t hauling much (how are you going to get a load of gravel 7 feet up into the bed?) and so they’ve got braking power to spare even with whatever weight increases related to the lift.
As for handling, well, I don’t think many of them would pass the moose test.
Well, (slight side rant) but most of the so-called rear wheel ABS systems are pretty useless. Essentially all they are is electronically-controlled proportioning valves that can adjusting the braking bias a little if it detects wheel slip. I’ve had a couple of trucks with the old mechanical load-sensing proportioning valves and a few with RWABS and I’ve never noticed a major difference between the two in terms of handling while braking.
(And, for a rant within a rant, many of the car makers still have an ABS light and badging on trucks that are only RWABS. This is IMHO really dangerous because if you try to stop a RWABS by holding the pedal down like you would with a true 4-wheel ABS system, you’re going to lock the wheels up. My 2007 Dodge truck is like that-- everything suggests it has ABS, but it took me sliding it into the ditch a couple of times in the first winter to realize it’s only RWABS and I’ve gotta pump those brakes!)