All other factors being equal (track width, wheelbase, overall weight, tires, etc.), a vehicle with a CG one or two inches higher is more likely to roll over. Semis roll over all the time. However, semis generally have a wider track that passenger vehicles and are driven by professional drivers who have enough sense to understand the limitations of their vehicles. Most vehicles will spin out before they turn over unless you do some really extreme maneuvers (quick changes in direction), there is an obstruction involved, or there is another vehicle involved.
But for how much longer? My family has owned nothing but Ford trucks for over 50 years. But when I needed to replace my trusty old F150, I wouldn't even consider the "new" F150. The bed sides are ridiculously high. If you get a 4x4, you have to have a step ladder to put anything in the truck's bed. I suppose this is fine for people who cover the bed with a hard tonneau cover and drive the vehicle around town, but for someone who actually has to use the truck as a truck, it sucks. Like I said before, if I wanted a Chevrolet Truck, I would have bought a Chevrolet truck. Ford out sold Chevrolet becasue they built better trucks, not becasue they made trucks that were thrird rate cars. Apparently they have forgotten this. I think they should just admit that F150s are just cars and rename them Taurus. The only thing that will save Ford is that they still sell F250s and the fact that Toyota still can't figure out how to build a decent full size pick-up.
It could. It depends on more than just the wheel size. Now if they both have the same type of suspension (type, pumpkin size etc.) and body, then 17" wheels with the correct size tires should have more ground clearance than 16 wheels with comparable size tires. In other words, P235R70-17 tires have a larger diameter than P235R70-16 tires and should provide greater ground clearance. However wheel size is only part of the equation when determining ground clearance. For example, P265/70R15 tires have a greater diameter than P245/65R17 and would therefore provide greater ground clearance, all other factors being equal. If you start considering other factors (independent suspension versus stick axles, body parts, steps, etc., etc.) it is very easy to find vehicles with 16" or 15" wheels with greater ground clearance than vehicles with 17" wheels.
No vehicle other than a two wheeler is prone to rollover, none. The difference in the center of gravity of a few inches is negligible. To make a vehicle roll it needs to be tipped up over 45 degrees. Watch movies or TV and you will see the will spin 360 degrees and do not roll, To make one roll the FX guys must run one side up on a four foot ramp. Striking an object and rolling is a result of inertia rather than the center of gravity. ;)
"Mike Hunter" wrote in message news:- snipped-for-privacy@ptd.net...
Define "prone" to rollover. Vehicles roll over all the time. You don't need a four foot ramp either. I've seen a VW Bug roll over in a flat parking lot - it didn't even hit the curbing. Get almost any vehicle sliding sideways and then have it contact something no higher than a curb, and tell me you can't roll one over. And if you think a higher CG doesn't make this more likely, then you need to take a remedial physics course. Tipping a vehicle 45 degrees is not required. If the COG is high enough, you can tip one that is not moving by tipping it at relatively small angles. Do a diagram showing the CG relative to the wheels. As soon as you tip the vehicle enough for the CG to be outside the wheel edges, it will roll on over. For instances, an F150 has a 67 inch track. For the vehicle to be statically stable at a tilt angle of 45 degrees, the CG must be no higher than approximately 33.5". I would guess that as delivered the CG is less than 30 inches above the ground. For a 30 inch height, the truck should remain stable until the tilt angle is around 48 degrees (probably less, since tires flex). However, if your raise the CG to 40 inches (and don't change the track width), the truck would roll over if you tilt it to the side at an angle of around 40 degrees. Raise it to 50 inches (again without changing the track width), and the truck would roll over on it's side if you tilted it sideways at little more than 30 degrees. Dynamic situations are more complicated. In general tire loose traction before the forces are high enough to tip a vehicle over on a flat surface. However, if you are doing extreme maneuvers, you can induce a rollover by first shifting the CG one way as the suspension responds to the maneuver and then back the other way. Inertia is at play here. But again, the higher the CG, the more likely this type of rollover is (all other things being equal).
You are talking a static roll over situation. Dynamic, when centrifugal force is involved and the bottom of a wheel on the outside goes up against resistance such as a road shoulder or curb, etc. is what normally causes roll over. A high center of gravity makes dynamic roll over more likely, just a inch higher is all it takes.
If you believe those set up movies and vehicle ads you believe anything. Unfortunately many do believe the ads and buy a vehicle that gets them into roll over problems.
In what way was I not "real?" It is very easy to find tires mounted on
15 inch rims that have a greater diameter than different tires mounted on 1 inch rims. Cross section width and aspect ratio must e considered when calculating the overall outside diamete. For a stick axle, the outside diamter of the tire is the most improtant factor in determining ground clearance.
Look it up in a dictionary. You are entitled to you own opinion but not your own facts. I worked as an automotive design engineer for thirty years. The center of gravity of a vehicle is located at a point below the center line of the mass of the drive train. If what you believe were actually true we should expect to see a few six wheelers on their side every day. ;)
You are entitled to you own opinion but I guess you missed the part about the effect of inertia in a rollover. The fact that the center of gravity is an inch or so higher has little effect ;)
What I said in my post was a larger wheel with a larger tire. The fact is contrary to the poster observation, no stock Ranger in any configuration, is the ground clearance lower than an F150 of a similar type, period.
I am not sure what a "six wheeler" is. Are you talking about pickups like an F350 with dual rear wheels? We do see trucks on there side almost every day. There is no way you can claim that every truck loaded/unloaded truck has a CG below "the center line of the mass of the drive train." That statement doesn't even make sense. Are you trying to say the CG of the total vehicle is lower than the CG of the drive train? This may or may not be true for an unloaded truck. For a six wheeler loaded with rock, I am sure it is false. On the other hand, it you are talking about a pick-up with dual rear wheels, then the effective track width has been greatly increased, and this will reduce the tendency to roll over.
Of course raising the CG has an effect. The magnitude of the effect depends on the intial CG, the wheelbase and many other factors. However, if all other factors are equal, raising the CG will increase the risk of a rollover.
Well I guess we make a fine pair. You seem sure of a lot of things that are not supported by facts.
Now educate me - what is a "six wheeler." It is not a term I hear. Is it a duallie - two front tires on a single front axle and four rear tires on a single rear axle with the tires arranged in pairs on either side or is a "six wheeler" two front tires on an axle and two rear axles with two tires each, or what? I know what a duallie is, a sixteen wheeler, a ten wheeler, etc. I've just never heard of a six wheeler (well except for the old formula one six wheeler - but I am sure you are not talking about that).
I think you need to reword this statement. Are you trying to say No Stock Ranger in any configuration has greater ground clearance that any F150 of a similar type? And by similar type do you mean any 4x4 Ranger compared to any
4x4 F150? Are you sure this is supported by the facts?
You might want to review the data at
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and verify you are making a true statement. At least this time, you are mostly correct if you take a very narrow definition of what "similar type" means. The Ranger with the greatest ground clearance (4x4 FX4 Level II Package with
31x10.50R-15SL Tires) has a minimum ground clearance of 8.3 inches. An F-150 Regular Cab 4x4 Styleside with P235/75R-17A/T Tires also has a ground clearance of 8.3". An F-150 Regular Cab 4x4 Styleside with P255/70R-17A/T Tires has a ground clearance of 8.2" So if you are comparing any Ranger 4x4 to any F150 4x4, the Ranger may have more ground clearance. A Ranger 4x4 without the FX4 Stage II package has 7.8" of clearance (less with a 4.0L) - which is less that a standard F150 4X4 with P235/75R-17A/T Tires. There are other F150 tire/wheel options that have greater ground clearance. To be clear, I am measuring ground clearance to the bottom of the rear differential. You will need to subtract the "K" dimension (the differential CL to bottom of the differential dimension) from CC dimension (the rear axle centerline height) to calculate this value. For the Ranger FX4 Stage II you need to refer to the tire data sheet to get the "CC" value for the tires on this model and use 5.7" for the "K" value since the FX4 Stage II package gets the larger differential. The standard Ranger differential hangs down
0.7 inches less than the standard F150 differential. So even though the radius of the F150 tire is greater than for the Ranger tires - 14.1" vs
12.9", the actual difference in ground clearance is less, 8.3" vs 7.8" (unless you have a 4.0 Ranger, then the differential is the same as for an F150 and the ground clearance is further reduced - unless you get the larger tires in the FX4 Stage II package).
BTW, the factory F150 with the greatest ground clearance uses the optional LT275/65R18C wheel/tire combination.
Heaven forbid they make a truck for WORK! Trucks werent designed for driving to the grocery store... they were designed for WORK... and when these trucks bottom out on small rocks in the woods, we have a problem.
The cross members in the new F150's on all the F150's at work are all beat in and bent back from bottoming out. I have driven these trucks, and they would barley clear a soda can sitting upright on a flat surface...
The ranger's at work are much higher... much to my surprise... and i am NOT an fan of rangers...
I am talking about 2wd trucks here, rangers w/ 235/75/15 and F150's with
255/70/17's
Ranger has more clearance, and i'm not talk>> What I said in my post was a larger wheel with a larger tire. The fact
Depends where you work. This is the first pickup i've ever seen that is not made to travel in the woods.
So now they need to make two 2wd models, one lower for you people who WORK in urban spaces and drive on the pavement and a second model for people who WORK in the woods.
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