Can a 205/65-10 Trailer Tire Fit in Place of a 5.70 x 8 Trailer Tire on a Popup Camper

Updated 07/30/2012 | Published 07/28/2012

Question:

Hi, my popup trailer sticker lists the tire/wheel specs as 20.5x8.10 on 10x6 5 lug wheel. My trailer has 5.70x8 tires installed, which is what the manual specifies. Which should I be using? I would prefer to use the more common size, and also to be able to slightly increase weight capacity. What do you recommend in this case. Load rating is C - 910 lbs.

asked by: Bill G

Expert Reply:

Provided that the manual for the camper and the camper itself match, that is unique problem. I am inclined to lean towards the sticker on the trailer in this case. But, to be sure, you will need to determine the axle capacity and choose the tires and load rating that match it.

The modern size for 20.5 x 8-10 is 205/65-10. This tire has a 20.5 inch diameter and it is about 8 inches wide. A 5.70 x 8 tire is 18.1 inches in diameter and is 5.7 inches wide so there is significant size difference. If there is space enough for the larger tire size you can still use it but it will not allow you to carry more weight because you are restricted to the axle capacity.

That is why you want to go by the axle capacity which should also be listed on the trailer. You can also go by the axle diameter to determine the capacity:

Typical Axle Diameters Based on Axle Capacity
1,000-lb - 2,000-lb Axles: 1-1/2 inch - 1-3/4 inch diameter
3,500-lb Axles: 2-3/8 inch diameter (Can have a 3-1/2 inch diameter, but rarely)
6,000-lb - 7,200-lb Axles: 3 inch diameter
8,000-lb Axles: 3-1/2 inch diameter
9,000-lb Axles: 4 inch diameter
10,000-lb Or more axles: 5 inch diameter