Bigger or smaller tire

Bigger. Slightly more foot print on the road

Yep, larger. less rolling resistance

Bigger is always better! Make sure you've got the clearance for larger tires, specifically, if you hit a bump, will they bottom out and rub the wheel well. That's the only thing you need to be concerned about. 5er and TT's don't have a way to track miles like in a car. So really, the larger foot print you can make, the better the ride for the trailer.

Tire diameter is a bit over 1" larger in diameter with the 245. Make sure the gap between the two tires is sufficient to allow the larger diameter.

I would go 225 E assuming it has a higher weight rating.

snowpeke wrote:
I am looking for a better tire than the 4 year towmax tires that I have on now. I have a 26.5 Jayco 5th wheel and GVWR is 9,950 it has 235/75/15 my tire guy says to get a E rated tire I have to go to a225/75/15 or 245/75/15 . Should I go big or smaller?

There are no ST235/75-15 or ST245-75 15 size tires on the market that I'm aware of.
Lots of ST225/75-15 D and E brands to choose from however I would look at the Providers.......Goodyear Endurance......Carlisle new HD all are the new gen ST tires with a L and M speed rating.

The benefit of a E tires comes at those higher pressures so if your trailer wheels can handle 80 psi the ST225/75-15 E gives your trailer a bit more reserve capacity to help fight stress as the tires slide (side scrub) around corners and a tire with less rolling resistance. If the wheels aren't rated for 80 psi then the better quality tires mentioned above in a ST D will work for you.

I have the same 5er, and went with 225/75/15 load E Kenda tires from trailer tires and wheels.

snowpeke wrote:
I am looking for a better tire than the 4 year towmax tires that I have on now. I have a 26.5 Jayco 5th wheel and GVWR is 9,950 it has 235/75/15 my tire guy says to get a E rated tire I have to go to a225/75/15 or 245/75/15 . Should I go big or smaller?

Michelin xps ribs... 225 75 16, a touch narrower and about 3/8 bigger diameter. New wheels involved though but really good long lasting tires.