Help with Towing Problem
09-30-2014, 12:08 PM
#1
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Help with Towing Problem
Hey,
I'm looking at putting a 2.5" Rough Country levelling kit w/ 35" Duratracs on my stock 18" rims. I have a 2010 FX4 5.4L.
I tow a 28" Mallard Sport Trailer, with the lip I'm looking at about 32-33". Dry its about 4500lbs, full 5500-6000lbs.
My problem is that Im concerned that I will have to re-gear my truck if i go with the 35" tire option with the 2.5" level on my stock rims. I know that if I go with that option ill loose power and gas consumption. Will it be better if I just go with the 33" option and the level?
Im just super torn between the two options, any help will be greatly appreciated.
I'm looking at putting a 2.5" Rough Country levelling kit w/ 35" Duratracs on my stock 18" rims. I have a 2010 FX4 5.4L.
I tow a 28" Mallard Sport Trailer, with the lip I'm looking at about 32-33". Dry its about 4500lbs, full 5500-6000lbs.
My problem is that Im concerned that I will have to re-gear my truck if i go with the 35" tire option with the 2.5" level on my stock rims. I know that if I go with that option ill loose power and gas consumption. Will it be better if I just go with the 33" option and the level?
Im just super torn between the two options, any help will be greatly appreciated.
09-30-2014, 12:19 PM
#3
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Im not sure of the gearing, but I plan on pulling 10-15 times in the summer. Roads would be mostly highway and flat with no huge elevation. We have one big trip planned next summer thats about 1900km one way.
10-02-2014, 10:36 AM
#4
Grumpy Old Man
Most so-called 35s, including the DuraTrac, are 34.6" diameter. But mounting that tire on your stock rims is not a good idea. Your stock rims are 7.5" wide, and the 35" DuraTrac requires rims at least 9" wide. The closest DuraTrac to a 35" diameter is the LT325/65r18.
http://www.tirerack.com/tires/tires....8WDT&tab=Specs
So don't mount those tires on your stock rims. Buy the correct rims for your tires.
As to change in the numbers, the percentage change in the tire revolutions per mile will be the same percentage change in your speedo, odo, tripmeter, and effective rear axle ratio. Your stock tires have 644 revs/mile and the 35s have 601. 644 minus 601 = 43, divided by 644 = 7.15 %. So if your F-150 has 3.55 axle ratio, your effective ratio with the tall tires will be 3.30 = less leverage so less power and torque to the rear wheels. That's why folks with tall aftermarket tires think their truck has lost power and is now gutless. Also if your speedo is correct now, it will be 7.15% slow with the new tires. Indicated 70 MPH will be an actual 75.005 MPH = just enough to get you a ticket from Officer Bob who has his radar set on 75.000. You'll probably need a speed shop to correct your speedo, because the dealer can only change the speedo to match tire sizes that were optional on your truck. And 35s were not an option from the factory.
http://www.tirerack.com/tires/tires....8WDT&tab=Specs
So don't mount those tires on your stock rims. Buy the correct rims for your tires.
As to change in the numbers, the percentage change in the tire revolutions per mile will be the same percentage change in your speedo, odo, tripmeter, and effective rear axle ratio. Your stock tires have 644 revs/mile and the 35s have 601. 644 minus 601 = 43, divided by 644 = 7.15 %. So if your F-150 has 3.55 axle ratio, your effective ratio with the tall tires will be 3.30 = less leverage so less power and torque to the rear wheels. That's why folks with tall aftermarket tires think their truck has lost power and is now gutless. Also if your speedo is correct now, it will be 7.15% slow with the new tires. Indicated 70 MPH will be an actual 75.005 MPH = just enough to get you a ticket from Officer Bob who has his radar set on 75.000. You'll probably need a speed shop to correct your speedo, because the dealer can only change the speedo to match tire sizes that were optional on your truck. And 35s were not an option from the factory.
10-02-2014, 05:43 PM
#6
Hey,
I'm looking at putting a 2.5" Rough Country levelling kit w/ 35" Duratracs on my stock 18" rims. I have a 2010 FX4 5.4L.
I tow a 28" Mallard Sport Trailer, with the lip I'm looking at about 32-33". Dry its about 4500lbs, full 5500-6000lbs.
My problem is that Im concerned that I will have to re-gear my truck if i go with the 35" tire option with the 2.5" level on my stock rims. I know that if I go with that option ill loose power and gas consumption. Will it be better if I just go with the 33" option and the level?
Im just super torn between the two options, any help will be greatly appreciated.
I'm looking at putting a 2.5" Rough Country levelling kit w/ 35" Duratracs on my stock 18" rims. I have a 2010 FX4 5.4L.
I tow a 28" Mallard Sport Trailer, with the lip I'm looking at about 32-33". Dry its about 4500lbs, full 5500-6000lbs.
My problem is that Im concerned that I will have to re-gear my truck if i go with the 35" tire option with the 2.5" level on my stock rims. I know that if I go with that option ill loose power and gas consumption. Will it be better if I just go with the 33" option and the level?
Im just super torn between the two options, any help will be greatly appreciated.
The following 2 users liked this post by daveak:
130428 (10-02-2014),
Wannafbody (10-02-2014)
10-03-2014, 10:13 AM
#7
Grumpy Old Man
Good decision if you don't want to buy new wheels. Your stock wheels will work fine with the width of the 275/70R18s.
And the taller tires change your effective axle ratio and speedo by only 2.6%, or less than 2 MPH at an indicated 70 MPH. Your trip meter will also be slow by 2.6%, so if you hand calculate MPG, you'll need to add 2.6% back to the indicated mileage if you want accurate MPG results.
