Originally Posted by donanddona
I don't think you will need it. Really, the dual axels allow to drive on three tires. You do need to remove the flat and keep your speed at a minimum but I have done it for 30 miles. A couple of gawkers, one from the state boys, I just nodded and they didn't stop me. A major tow service in my area (interstate) told me that's the way they do it if at all possible. Additionally, I've only used the spare when one of the other tires was beyond usage. Good luck..
Don't forget that when you run with just one tire on a side of a trailer that has tandem axles you are running at about 100% overload. While tires may be able to tolerate this for a few miles this does not me you aren't doing significant internal structural damage to the remaining tire. This will definitely shorten the tire life and you may experience a failure a few month later.
When you run overloaded the molecular bonds in the rubber break down and microscopic cracks form. These cracks will not repair themselves but will provide focal points for increases levels of stress for the rest of the tire's life.
On june 12 2012,I did a post on my blog on "limping home" when one tire in a dual pair fails. The damage to the remaining tire on a multi axle trailer is much the same.
I write a blog on RV tire application and safety. RVTireSafety.com
Also give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV