Sounds like your relatively close to maxxing out the vehicles rated capabilities, and with the modifications, it could put you at risk. Here is GM's info, it is also in your owners manual.
Towing a Trailer
Do not tow a trailer during break-in. See New Vehicle Break-In for more information.
Warning: The driver can lose control when pulling a trailer if the correct equipment is not used or the vehicle is not driven properly. For example, if the trailer is too heavy, the brakes may not work well -- or even at all. The driver and passengers could be seriously injured. The vehicle may also be damaged; the resulting repairs would not be covered by the vehicle warranty. Pull a trailer only if all the steps in this section have been followed. Ask your dealer/retailer for advice and information about towing a trailer with the vehicle.
Notice: Pulling a trailer improperly can damage the vehicle and result in costly repairs not covered by the vehicle warranty. To pull a trailer correctly, follow the advice in this section and see your dealer/retailer for important information about towing a trailer with the vehicle.
To identify the trailering capacity of the vehicle, read the information in "Weight of the Trailer" that appears later in this section.
Trailering is different than just driving the vehicle by itself. Trailering means changes in handling, acceleration, braking, durability and fuel economy. Successful, safe trailering takes correct equipment, and it has to be used properly.
The following information has many time-tested, important trailering tips and safety rules. Many of these are important for your safety and that of your passengers. So please read this section carefully before pulling a trailer.
Pulling A Trailer
Here are some important points:
" There are many different laws, including speed limit restrictions, having to do with trailering. Make sure the rig will be legal, not only where you live but also where you will be driving. A good source for this information can be state or provincial police.
" Consider using a sway control. See "Hitches" later in this section.
" Do not tow a trailer at all during the first 500 miles (800 km) the new vehicle is driven. The engine, axle or other parts could be damaged.
" Then, during the first 500 miles (800 km) that a trailer is towed, do not drive over 50 mph (80 km/h) and do not make starts at full throttle. This helps the engine and other parts of the vehicle wear in at the heavier loads.
" Vehicles can tow in D (Drive). Shift the transmission to a lower gear if the transmission shifts too often under heavy loads and/or hilly conditions.
Important considerations that have to do with weight:
" The weight of the trailer
" The weight of the trailer tongue
" The weight on the vehicle's tires
" And the weight of the trailering combination
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how the rig is used. Speed, altitude, road grades, outside temperature and how much the vehicle is used to pull a trailer are all important. It can depend on any special equipment on the vehicle, and the amount of tongue weight the vehicle can carry. See "Weight of the Trailer Tongue" later in this section for more information.
Trailer weight rating (TWR) is calculated assuming the tow vehicle has only the driver but all required trailering equipment. Weight of additional optional equipment, passengers and cargo in the tow vehicle must be subtracted from the trailer weight rating.
Use the following chart to determine how much the vehicle can weigh, based upon the vehicle model and options.
Maximum Trailer Weight
7,500 lbs (3 402 kg)
14,000 lbs (6 350 kg)
*The Gross Combination Weight Rating (GCWR) in the total allowable weight of the completely loaded vehicle and trailer including any passengers, cargo, equipment and conversions. The GCWR for the vehicle should not be exceeded.
Ask your dealer/retailer for trailering information or advice, or write us at our Customer Assistance Offices. See Customer Assistance Offices for more information.
Weight of the Trailer Tongue
The tongue load (A) of any trailer is very important because it is also part of the vehicle weight. The Gross Vehicle Weight (GVW) includes the curb weight of the vehicle, any cargo carried in it, and the people who will be riding in the vehicle as well as trailer tongue weight. Vehicle options, equipment, passengers and cargo in the vehicle reduce the amount of tongue weight the vehicle can carry, which will also reduce the trailer weight the vehicle can tow. See Loading the Vehicle for more information about the vehicle's maximum load capacity.
Trailer tongue weight (A) should be 10 percent to 15 percent and fifth wheel or gooseneck kingpin weight should be 15 to 25 percent of the loaded trailer weight up to the maximums for vehicle series and hitch type shown below:
Maximum Tongue Weight
272 kg (600 lbs)
499 kg (1,100 lbs)
Do not exceed the maximum allowable tongue weight for the vehicle. Choose the shortest hitch extension that will position the hitch ball closest to the vehicle. This will help reduce the effect of trailer tongue weight on the rear axle.
Trailering may be limited by the vehicle's ability to carry tongue weight. Tongue or kingpin weight cannot cause the vehicle to exceed the GVWR (Gross Vehicle Weight Rating) or the RGAWR (Rear Gross Axle Weight Rating). See "Total Weight on the Vehicle's Tires" later in this section for more information.
After loading the trailer, weigh the trailer and then the tongue, separately, to see if the weights are proper. If they are not, adjustments might be made by moving some items around in the trailer.
Total Weight on the Vehicle's Tires
Be sure the vehicle's tires are inflated to the inflation pressures found on the Certification label on the drivers door or see Loading the Vehiclefor more information. Make sure not to exceed the GVWR limit for the vehicle, or the RGAWR, with the tow vehicle and trailer fully loaded for the trip including the weight of the trailer tongue. If using a weight distributing hitch, make sure not to exceed the RGAWR before applying the weight distribution spring bars.
Weight of the Trailering Combination
It is important that the combination of the tow vehicle and trailer does not exceed any of its weight ratings -- GCWR, GVWR, RGAWR, Trailer Weight Rating or Tongue Weight. The only way to be sure it is not exceeding any of these ratings is to weigh the tow vehicle and trailer combination, fully loaded for the trip, getting individual weights for each of these items.
The correct hitch equipment helps maintain combination control. Most small-to-medium trailers can be towed with a weight carrying hitch which simply features a coupler latched to the hitch ball. Larger trailers may require a weight distributing hitch that uses spring bars to distribute the trailer tongue weight among the two vehicle and trailer axles. See "Weight of the Trailer Tongue" earlier in this section for rating limits with various hitch types.
If a step-bumper hitch will be used, the bumper could be damaged in sharp turns. Make sure there is ample room when turning to avoid contact between the trailer and the bumper.
Consider using sway controls with any trailer. Ask a trailering professional about sway controls or refer to the trailer manufacturer's recommendations and instructions.
Weight-Distributing Hitch Adjustment
A: Body to Ground Distance
B: Front of Vehicle
When using a weight-distributing hitch, the spring bars should be adjusted so the distance (A) is the same after coupling the trailer to the tow vehicle and adjusting the hitch.
Always attach chains between the vehicle and the trailer. Cross the safety chains under the tongue of the trailer to help prevent the tongue from contacting the road if it becomes separated from the hitch. Instructions about safety chains may be provided by the hitch manufacturer or by the trailer manufacturer. If the trailer being towed weighs up to 5,000 lbs (2 271 kg) with a factory-installed step bumper, safety chains may be attached to the attaching points on the bumper, otherwise, safety chains should be attached to holes on the trailer hitch platform. Always leave just enough slack so the combination can turn. Never allow safety chains to drag on the ground.
Pressing this button at the end of the shift lever turns on and off the tow/haul mode.
This indicator light on the instrument panel cluster comes on when the tow/haul mode is on.
Tow/Haul is a feature that assists when pulling a heavy trailer or a large or heavy load. See Tow/Haul Mode for more information.
Tow/Haul is designed to be most effective when the vehicle and trailer combined weight is at least 75 percent of the vehicle's Gross Combined Weight Rating (GCWR). See "Weight of the Trailer" earlier in the section. Tow/Haul is most useful under the following driving conditions:
" When pulling a heavy trailer or a large or heavy load through rolling terrain.
" When pulling a heavy trailer or a large or heavy load in stop and go traffic.
" When pulling a heavy trailer or a large or heavy load in busy parking lots where improved low speed control of the vehicle is desired.
Operating the vehicle in Tow/Haul when lightly loaded or with no trailer at all will not cause damage. However, there is no benefit to the selection of Tow/Haul when the vehicle is unloaded. Such a selection when unloaded may result in unpleasant engine and transmission driving characteristics and reduced fuel economy. Tow/Haul is recommended only when pulling a heavy trailer or a large or heavy load.
A loaded trailer that weighs more than 2,000 lbs (900 kg) needs to have its own brake system that is adequate for the weight of the trailer. Be sure to read and follow the instructions for the trailer brakes so they are installed, adjusted and maintained properly.
Since the vehicle is equipped with StabiliTrak , the trailer brakes cannot tap into the vehicle's hydraulic system.
Driving with a Trailer
Warning: When towing a trailer, exhaust gases may collect at the rear of the vehicle and enter if the liftgate, trunk/hatch, or rear-most window is open.
Engine exhaust contains carbon monoxide (CO) which cannot be seen or smelled. It can cause unconsciousness and even death.
To maximize safety when towing a trailer:
" Have the exhaust system inspected for leaks and make necessary repairs before starting a trip.
" Never drive with the liftgate, trunk/hatch, or rear-most window open.
" Fully open the air outlets on or under the instrument panel.
" Adjust the Climate Control system to a setting that brings in only outside air and set the fan speed to the highest setting. See Climate Control System in the Index.
For more information about carbon monoxide, see Engine Exhaust.
Towing a trailer requires a certain amount of experience. The combination you are driving is longer and not as responsive as the vehicle itself. Get acquainted with the handling and braking of the rig before setting out for the open road.
Before starting, check all trailer hitch parts and attachments, safety chains, electrical connectors, lamps, tires and mirrors. If the trailer has electric brakes, start the combination moving and then apply the trailer brake controller by hand to be sure the brakes work.
During the trip, check occasionally to be sure that the load is secure and the lamps and any trailer brakes still work.
Stay at least twice as far behind the vehicle ahead as you would when driving the vehicle without a trailer. This can help to avoid heavy braking and sudden turns.
More passing distance is needed when towing a trailer. The combination will not accelerate as quickly and is longer so it is necessary to go much farther beyond the passed vehicle before returning to the lane.
Hold the bottom of the steering wheel with one hand. Then, to move the trailer to the left, move that hand to the left. To move the trailer to the right, move your hand to the right. Always back up slowly and, if possible, have someone guide you.
Notice: Making very sharp turns while trailering could cause the trailer to come in contact with the vehicle. The vehicle could be damaged. Avoid making very sharp turns while trailering.
When turning with a trailer, make wider turns than normal. Do this so the trailer will not strike soft shoulders, curbs, road signs, trees or other objects. Avoid jerky or sudden maneuvers. Signal well in advance.
If the trailer turn signal bulbs burn out, the arrows on the instrument panel will still flash for turns. It is important to check occasionally to be sure the trailer bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gear before starting down a long or steep downgrade. If the transmission is not shifted down, the brakes might get hot and no longer work well.
Vehicles can tow in D (Drive). Shift the transmission to a lower gear if the transmission shifts too often under heavy loads and/or hilly conditions.
The tow/haul mode may be used if the transmission shifts too often. See Tow/Haul Mode.
When towing at high altitude on steep uphill grades, consider the following: Engine coolant will boil at a lower temperature than at normal altitudes. If the engine is turned off immediately after towing at high altitude on steep uphill grades, the vehicle may show signs similar to engine overheating. To avoid this, let the engine run while parked, preferably on level ground, with the automatic transmission in P (Park) for a few minutes before turning the engine off. If the overheat warning comes on, see Engine Overheating.
Parking on Hills
Warning: Parking the vehicle on a hill with the trailer attached can be dangerous. If something goes wrong, the rig could start to move. People can be injured, and both the vehicle and the trailer can be damaged. When possible, always park the rig on a flat surface.
If parking the rig on a hill:
Press the brake pedal, but do not shift into P (Park) yet. Turn the wheels into the curb if facing downhill or into traffic if facing uphill.
Have someone place chocks under the trailer wheels.
When the wheel chocks are in place, release the regular brakes until the chocks absorb the load.
Reapply the brake pedal. Then apply the parking brake and shift into P (Park).
Release the brake pedal.
Warning: It can be dangerous to get out of the vehicle if the shift lever is not fully in P (Park) with the parking brake firmly set. The vehicle can roll.
If the engine has been left running, the vehicle can move suddenly. You or others could be injured. To be sure the vehicle will not move, even when on fairly level ground, always put the shift lever fully in P (Park) with the parking brake firmly set.
Leaving After Parking on a Hill
Apply and hold the brake pedal.
Start the engine
Shift into a gear
Release the parking brake
Let up on the brake pedal.
Drive slowly until the trailer is clear of the chocks.
Stop and have someone pick up and store the chocks.
Maintenance When Trailer Towing
The vehicle needs service more often when pulling a trailer. See this manual's Maintenance Schedule or Index for more information. Things that are especially important in trailer operation are automatic transmission fluid, engine oil, axle lubricant, belts, cooling system and brake system. It is a good idea to inspect these before and during the trip.
Subtract the hitch loads from the Cargo Weight Rating (CWR). CWR is the maximum weight of the load the vehicle can carry. It does not include the weight of the people inside, but you can figure about 150 lbs. (68 kg) for each passenger. The total cargo load must not be more than the vehicles CWR.
Weigh the vehicle with the trailer attached, so the GVWR or GAWR are not exceeded. If using a weight-distributing hitch, weigh the vehicle without the spring bars in place.
The best performance is obtained by correctly spreading out the weight of the load and choosing the correct hitch and trailer brakes.
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Thursday, June 18th, 2009 AT 11:17 PM