Speed Rating of Trailer Tires in Size 5.70-8

Updated 03/14/2018 | Published 03/12/2018

Question:

Hi, We just bought the Kenda trailer tires 5.70-8, 4x4, C rating, rated at 65 mph. We will be towing boat on highway to Fort Lauderdale, Florida. We are concerned that we may be run over going only 65 mph. If we inflate them 10 more, we read that you can drive a little faster. Is that true? Thank you.

asked by: Karen &

Expert Reply:

No, unfortunately it is not true that over-inflating a tire allows it to be driven faster, nor can it carry more weight. It is never appropriate to under- or over-inflate a trailer tire for any reason.

Trailer tires should ALWAYS be inflated to the maximum cold psi pressure indicated on the tire sidewall. This means that at the start of the day when the tires are cold you want to ensure they have that full specified pressure, no more, no less.

It is normal for tires to warm up from friction as you drive; it is also normal for tires to have their pressure increase slightly as the outside temperature increases. In general, a 10-degree Fahrenheit temperature change will result in a 1-lb pressure change. You do not need to adjust for this during the day's driving but do make sure each morning that your starting cold pressure is right on spec.

What tends to kill a trailer is excess heat. Excess heat can come about from three main causes: incorrect inflation pressure, overloading the tire beyond its weight capacity or driving it faster than it is rated to go. Avoiding all of these pitfalls is the best way to ensure your safety and hassle-free trailer towing.

The wheel/tire you purchased, Kenda 5.70-8 Bias Trailer Tire/Wheel # AM30120 can handle up to 910-lbs at its rated 75-psi pressure. But this tire is rated for 65-mph maximum. None of our tires in size 5.70-8 are rated for more than 65-mph.

expert reply by: Adam R