Re: Can't find this tire
That E70/14 size is just an older bias ply tire size, the comparable tire size would be a 195 or maybe a 205/70-14.
Trailer tires are the right choice, but when they aren't available, sometimes you have to make do.
It seems that 14" tires are becoming extinct, I've also had trouble finding a few larger 13" sizes and many 15" tires lately. No one stocks them anymore since all the newer cars use 16" and larger wheels.
Most farm centers and RV centers keep the trailer tires in stock, but they can be pricey. We have a TSC here that keeps them in quanity at a decent price, but no 14" at all, only 13" and 15". I switched over to 13" on two of my trailers for that same reason, it also lowers my boat to a better launching height. Weight wasn't a concern, so changing sizes didn't affect that at all.
