All too often folks just want to know what their vehicle can safely tow. Manufacturer tow ratings are misleading because these ratings do not account for any additional weight added to the tow vehicle. Any weight added to the tow vehicle must be subtracted from the published tow rating. This includes the weight of all passengers, all cargo, aftermarket equipment added to the vehicle and the tongue weight or pin weight of the travel trailer or 5th wheel trailer you are towing. In some cases the actual tow rating can be 4,000 pounds lower than the vehicle manufacturers published tow rating. That’s right, 4000 pounds lower!
Even if you have a good understanding of how this works you can still get lost in all the terminology involved in calculating a safe tow rating for your vehicle. There are acronyms like GVWR, GAWR, GVW, GCWR, GTW, MLTWR, UVW, CW, TW and HW just to name a few.
It seems ridiculous to me that a person is expected to understand all of this complicated jargon so they can figure out what is safe and what’s not safe when it comes to towing a travel trailer or 5th wheel.
And, unfortunately the end result of using vehicle manufacturer published tow ratings, as a measure for safe towing, is grossly overloaded tow vehicles and mismatched tow vehicle and trailer combinations. This can be extremely dangerous to the occupants in the tow vehicle and to other people in the vicinity of these mismatched combinations traveling down the highway.
To help solve this problem and make it much easier to calculate a safe tow rating for your vehicle I have devised simple and safe towing formulas that will work in nearly all scenarios.
Note: These simple & safe towing formulas are designed to eliminate the complicated calculations and terminology and to give you a quick picture of a safe tow rating for your particular tow vehicle. They may not be 100% foolproof but in the majority of cases will determine a properly matched tow vehicle and trailer.
I refer to these towing formulas as Polk’s 80/20 and 75/25 simple & safe towing formulas. The 80/20 towing formula is used for vehicles towing conventional trailers and the 75/25 towing formula is used for vehicles towing 5th wheel trailers.
Here’s how they work:
Polk’s 80/20 Trailer Towing Formula:
Vehicle tow rating X 80% – 20% = the maximum dry or unloaded trailer weight you can tow.
Let’s look at a sample vehicle. Here are all the stats:
Vehicle Tow Rating = 8750 lbs.
Gross Vehicle Weight Rating (GVWR) = 6,800 lbs.
Vehicle Payload = 1,695 lbs.
Vehicle Curb Weight (CW) = 5,105 lbs.
Gross Axle Weight Rating (GAWR) Front/Rear = 3,700 lbs / 3,900 lbs.
Gross Combined Weight Rating (GCWR) = 14,000
Now let’s apply Polk’s 80/20 Trailer Towing Formula:
8,750 lb. tow rating X 80% = 7,000 lbs. – 20% = 5,600 lb. maximum trailer dry weight you can tow.
Now let’s cross check these figures to see if this is safe match:
Calculate Tongue Weight (TW): 5,600 lb. trailer X 15% TW = 840 lbs.
5,105 lb. CW + 840 lb. TW + 600 lb. passengers and cargo = 6,545 lb. Gross Vehicle Weight (GVW) which is under the vehicles 6,800 lb. GVWR.
840 lb. TW + 600 lb. passengers & cargo = 1,440 lbs. which is under the vehicles 1,695 lb. payload.
Calculate Gross Trailer Weight (GTW): 5,600 lb. dry trailer weight + 1,200 lb. of added cargo = 6,800 lbs. GTW
6,800 lb. GTW + 6,545 lb. GVW = 13,345 lbs. which is under the 14,000 lb. vehicle GCWR
Polk’s 75/25 5th Wheel Towing Formula
Vehicle Tow rating X 75% – 25% = the max dry or unloaded weight of a 5th wheel trailer you can tow.
Let’s look at a sample vehicle. Here are all the stats:
Vehicle Tow Rating 13,800
Vehicle Gross vehicle Weight Rating (GVWR) = 11,500 lbs.
Vehicle Payload = 4,442 lbs.
Vehicle Curb Weight (CW) = 7,058 lbs.
Vehicle Gross Axle Weight Rating (GAWR) Front/Rear = 4,750 lbs / 9,350
Vehicle Gross Combined Weight Rating (GCWR) = 21,000
Now let’s apply Polk’s 75/25 5th Wheel Towing Formula:
13,800 X 75% =10,350 lbs. – 25% = 7,762 lbs maximum 5th wheel trailer dry you can tow.
Now let’s cross check theses figures to see if this is safe match:
Calculate Hitch Pin Weight (HW): 7,762 lb. trailer X 25% HW = 1,940 lbs. HW
7,058 lb. CW + 1,940 lb. HW + 600 lb. passengers and cargo = 9,598 lbs. Gross Vehicle Weight (GVW) which is under the vehicle 11.500 lb. GVWR.
1,940 lb. HW + 600 lb. passengers & cargo = 2,540 lbs. which is under the vehicles 4,442 lb. payload.
Calculate Gross Tailer Weight (GTW): 7,762 lb. dry trailer weight + 1,200 lb. of added cargo = 8,962 lbs. GTW
8,962 lb. GTW + 9,598 lb. GVW = 18,560 lbs. which is under the 21,000 lb. vehicle GCWR
Note: These simple & safe towing formulas will work in most towing application as long as the owner does not grossly overload the tow vehicle or trailer with additional weight. Keep in mind it is much easier to exceed weight ratings on smaller tow vehicles like mini vans and small SUVs. Always make sure you cross check all towing calculation prior to attempting to tow any trailer.
Happy RV Learning,
Mark Polk
Copyright by Mark Polk owner of RV Education 101 – All Rights Reserved
Mark Polk
How can you presume to know more about a vehicles tow rating better than the vehicle manufacturers?
According to your tow rating, my F250 Super duty, might as well pull a wagon, and not any of the fifth wheels that I have been researching.
I’ve also researched many RV blogs and sites of owners who have safely towed fifth wheels all over our country safely and who do not use your formula.
I have serious concerns as what motivated this article and how you came to use this “formula” and what it really represents.
By: David M Toney on 2012
at 2012
There are no hidden agendas with the article, just a concern with towing safety and helping educate folks on a complicated topic.
In a nut-shell my towing formulas help to account for additional weight added to the tow vehicle, an acceptable amount of tongue weight or hitch weight on the vehicle, and to avoid exceeding other important weight ratings.
As far as being qualified to speak on the subject I have been an expert witness in numerous cases where individuals lost their lives and were seriously injured due to mismatched tow vehicles and trailers. If I can prevent this from happening to one person through education I’ll talk about it all day long.
Feel free to tow whatever Ford claims your truck can safely tow.
By: Mark Polk on 2012
at 2012