Tongue Mounted Spare Tire on 172

When we bought our 172 we ordered the factory recommended bike rack for the rear. This displaced the spare tire. I didn’t want to give up interior storage space so I devised a way to mount the tire on the tongue. This was a bit of a task since the tongue already had two batteries, two propane tanks, and an equalizer hitch. However, it worked out well.

The job begins with a Swagman model 64025 RV Bumper Adapter, available from Amazon:

 http://www.amazon.com/Swagman-RV-2-Bumper-Adaptor/dp/B00174ZHGU/ref=sr_1_5?ie=UTF8&qid=1352492512&sr=8-5&keywords=swagman

This adapter is designed for a 4” square bumper so some work is required to mount it on the 2”x3” RPOD frame tubing. The attachment bolts are replaced with ½ x 4 ½ inch class 8 high strength bolts, flat washers, and locking nuts to accommodate the 3” frame depth. Two new 9/16” holes, spaced 3” center-to-center from two of the existing holes, are drilled in the top and bottom plates to accommodate the 2” frame width. I would have preferred stainless, but stainless is not as strong as the class 8 bolts so I went with SAE ½ inch bolts and locking nuts. I did replace the 10 mm hex set screw bolt with stainless, but be warned, it is metric. The starting kit is shown below:

The Swagman adapter provides a 2 inch receiver and the FR supplied tire carrier requires a 1.25 inch receiver. I used the reducer sleeve that came with the bike carrier, but similar devices are available elsewhere.

 The results are shown below. The adapter just fits, but it fits:

Happy podding.

Good job! Happy trails to you rex pHp stuart fla

Hi Goose. Thanks for the reply and your interest.

Although I didn't specifically weigh before and after, some approximations can be made. The replacement of the rear mounted spare tire with the two bikes and carrier is probably a wash. The bikes probably weigh slightly more than the tire and its carrier so this would tend to decrease tongue weight. However, the first alternate spare storage was inside the trailer under the front bunk so this added tongue weight. Moving the tire and carrier to the tongue adds directly to the tongue weight. I'm guessing this is 20-30 pounds including the Swagman bumper adapter.

Before I bought the R-Pod I did some spreadsheet calculations on total towed weight and tongue weight. Starting with the factory specifications I allowed for the second battery, second propane tank and 20# of propane, ordered options, and 10 gallons of fresh water for traveling. The calculated tongue weight totaled 357 pounds, which exceeds my bathroom scale capability, so I didn't weight the pod. My tow vehicle is rated 400-450 pounds tongue weight, depending on passenger load, so I am not too concerned. Also, with the E2 equalizer hitch, the effects of tongue weight are mitigated.

Bottom line is I don't have a really have a good measured weight, but no problems so far in 300-500 miles of towing. The E2 hitch really makes the difference.

Goose,

Further info on tongue weight on my 172. I finally rigged a 4x4 beam to split the tongue weight between a block and a bath scale and measured the tongue weight as loaded. The measurement was 293 pounds with 2 full propane tanks, 2 series 24 batteries and the spare tire on the tongue, and 2 bikes (60 pounds total) on the rear bumper. I also had 5-10 gallons of fresh water onboard, behind the axel, which would tend to unload the tongue. This is actually less than I expected from the 244# spec sheet value, but it’s not known exactly what that spec value includes. The total pod weight as measured at the factory before shipment included one empty propane tank and no batteries and the spare on the rear bumper. That measurement was 2407 pounds. Adding the known accessories such as extra propane and tanks, batteries, bikes and R-Dome I calculate total loaded weight to be 2742 pounds. Overall, with the 293# tongue weight which is about 11% of total, and the E2 hitch I am comfortable with the loading.