jharden1
07-30-2008, 06:26
My wife and I took a driving trip this June and I wanted to give everyone a data point.
The truck is a LMM 2007 Chevy 2500HD 4x4, Crew Cab short bed, Duramax /Allison. The only non stock items are a 51 Gallon fuel tank/ tool box combo by RDS and some cargo tie downs.
The truck weighs GVW7580, FAW4480/RAW3100, with the dog and I and 47 gals fuel on board. The truck and trailer weighs GVW15260, FAW4480/RAW4520/TW6240 with 76 gals fuel and 300 pounds of stuff. I use a load equalizing hitch. The trailer is a 1991 Travel trailer with two 6k axels, I had them put on after the stock 3.5k axels sagged. Notice that the truck is with in 180 pounds of gross weight max of 9200lbs. We used 432.4 gals of fuel, measured. The truck had 16980 miles to start trip. We drove 4762 miles for a calculated fuel mileage of 11.01 mpg, the DIC said 11.0.
We started in Ohio and drove to the Black Hills of South Dakota through IL, WI, MN. This was the first leg of the trip and I needed the first 250 miles to finish breaking in the rear end so I stayed at 60mph. The DIC was claiming 13.5 mpg during this period. Engine coolant temperature stayed at 210 and Transmission at 185. I had first mechanical problem, I discovered a low trailer tire on walk around, the valve in the stem was leaking.
Next leg was to Kremmling area of CO through Laramie, WY. Highest point during this leg was 9300 ft, grades were modest, maybe 3-4%. This is the first time I could tell the truck wasn’t loafing. We stayed at 8300 feet and I wanted to run the trailer tires at 75psi per Goodyear. When using a relative pressure gauge, most are, you have to compensate for altitude so you don’t have under inflated tires at sea level. It’s about .5 psi per thousand feet so I filled them to 79psi and all was good.
Next leg was to the four corners area on I70, then south through Moab, UT. This was old ground for me as I used to live in NW CO. I’ve been over I70 between Rifle and Denver about 800 times, about 400 of these in a 6.5TD GMC. We hit I70 at Silverthorne and headed west over Vail pass. I accelerated up the on ramp, it’s about 5-6%, and set the cruise at 70. The Allison down shifted to 5th once. Grade braking on the down hill side was just as easy although it’s a bit more curvy so I was running slower for that reason. I had pulled the same hills in my 6.5 and the difference was night and day. Engine temps were about 220 and tranny about 215 to 220. Oh…AC was on. The next hot spot was what the locals call Compressor Hill South of Moab. Its about 30 miles of steady3-5% grades and I saw 220 on the engine and 230 on the transmission, fan would engage and run steady here. There was always plenty of power for passing, but you had to respect your temps.
We drove back to OH in 3 days, almost 1900 mile. Vail pass and Eisenhower Tunnel east bound were easy, one is 11.3k the other is about 10.7k; I watched the temps and drove up and over them at 60-70 mph, which is at the speed limits. We had our second low trailer tire on the way back, a stem failure. I found this one on a walk around, too.
The fuel tank saved us about $100 dollars by letting us plan our daily fuel stop. I used mapquest and gasbuddy.com to pick the best locale for the stop. Then the wife and I would pick the one we stopped at based on price, appearance and bladder pressure. Fuel prices ranged from 4.47 to 5.11, I only paid 4.80 for one load, and the rest was about 4.55.
I have waited to post this because I wanted to see what the effect of the trip, if any, on the truck. I am averaging about 1 more mile per gallon on my driving mix. I now get 17.7 mpg on about the last 150 gals. The truck also feels a bit perkier.
We had a great trip and the truck performed flawlessly.
My one plug, do your safety checks, I have no doubt that they saved me two catastrophic tire failures. I’m thinking tire pressure monitors for the trailer. Happy Travels!
-Jim
The truck is a LMM 2007 Chevy 2500HD 4x4, Crew Cab short bed, Duramax /Allison. The only non stock items are a 51 Gallon fuel tank/ tool box combo by RDS and some cargo tie downs.
The truck weighs GVW7580, FAW4480/RAW3100, with the dog and I and 47 gals fuel on board. The truck and trailer weighs GVW15260, FAW4480/RAW4520/TW6240 with 76 gals fuel and 300 pounds of stuff. I use a load equalizing hitch. The trailer is a 1991 Travel trailer with two 6k axels, I had them put on after the stock 3.5k axels sagged. Notice that the truck is with in 180 pounds of gross weight max of 9200lbs. We used 432.4 gals of fuel, measured. The truck had 16980 miles to start trip. We drove 4762 miles for a calculated fuel mileage of 11.01 mpg, the DIC said 11.0.
We started in Ohio and drove to the Black Hills of South Dakota through IL, WI, MN. This was the first leg of the trip and I needed the first 250 miles to finish breaking in the rear end so I stayed at 60mph. The DIC was claiming 13.5 mpg during this period. Engine coolant temperature stayed at 210 and Transmission at 185. I had first mechanical problem, I discovered a low trailer tire on walk around, the valve in the stem was leaking.
Next leg was to Kremmling area of CO through Laramie, WY. Highest point during this leg was 9300 ft, grades were modest, maybe 3-4%. This is the first time I could tell the truck wasn’t loafing. We stayed at 8300 feet and I wanted to run the trailer tires at 75psi per Goodyear. When using a relative pressure gauge, most are, you have to compensate for altitude so you don’t have under inflated tires at sea level. It’s about .5 psi per thousand feet so I filled them to 79psi and all was good.
Next leg was to the four corners area on I70, then south through Moab, UT. This was old ground for me as I used to live in NW CO. I’ve been over I70 between Rifle and Denver about 800 times, about 400 of these in a 6.5TD GMC. We hit I70 at Silverthorne and headed west over Vail pass. I accelerated up the on ramp, it’s about 5-6%, and set the cruise at 70. The Allison down shifted to 5th once. Grade braking on the down hill side was just as easy although it’s a bit more curvy so I was running slower for that reason. I had pulled the same hills in my 6.5 and the difference was night and day. Engine temps were about 220 and tranny about 215 to 220. Oh…AC was on. The next hot spot was what the locals call Compressor Hill South of Moab. Its about 30 miles of steady3-5% grades and I saw 220 on the engine and 230 on the transmission, fan would engage and run steady here. There was always plenty of power for passing, but you had to respect your temps.
We drove back to OH in 3 days, almost 1900 mile. Vail pass and Eisenhower Tunnel east bound were easy, one is 11.3k the other is about 10.7k; I watched the temps and drove up and over them at 60-70 mph, which is at the speed limits. We had our second low trailer tire on the way back, a stem failure. I found this one on a walk around, too.
The fuel tank saved us about $100 dollars by letting us plan our daily fuel stop. I used mapquest and gasbuddy.com to pick the best locale for the stop. Then the wife and I would pick the one we stopped at based on price, appearance and bladder pressure. Fuel prices ranged from 4.47 to 5.11, I only paid 4.80 for one load, and the rest was about 4.55.
I have waited to post this because I wanted to see what the effect of the trip, if any, on the truck. I am averaging about 1 more mile per gallon on my driving mix. I now get 17.7 mpg on about the last 150 gals. The truck also feels a bit perkier.
We had a great trip and the truck performed flawlessly.
My one plug, do your safety checks, I have no doubt that they saved me two catastrophic tire failures. I’m thinking tire pressure monitors for the trailer. Happy Travels!
-Jim