Tire Size Assistance

[tedder]

I'm looking to replace my tires and everywhere I go the tire sizes are 175-80-13 or something similar to car tire sizes.<br /><br />The size on my trailer tire says B78-13ST. Can someone convert that into english for me?<br /><br />I know the "B" is the load rating.<br /><br />Also wondering if its a better idea to go with a radial than a bias ply?<br /><br />Cheers

 

[Dunaruna]

Re: Tire Size Assistance

The B78 has a 78% aspect ratio (sidewall to tread). You need to change to either 80 or 75.<br /><br />B78x13 is equivilent to - <br /><br />Bias ply - 6.50x13<br /><br />Radial ply - 185/ 75 x13 or 175/ 80 x13. <br /><br />You'll be fine with the 175/80x13ST.

 

[tedder]

Re: Tire Size Assistance

I was hoping to get this done today so thanks very much for the quick response.

 

[summerwind1991]

Re: Tire Size Assistance

Got me thinking if the tires on the used trailer I had purchased are car or trailer tires. LTD Easy Rider P185/80RI3, 35 PSI. Indicates Standard Load Max. Would you happen to know? I am unable to find anything on the internet on these.

 

[Silvertip]

Re: Tire Size Assistance

"P" designates "passenger car". The other tip off is 35PSI maximum. Trailer tires are typically rated at 50PSI max to resist sidewall flexing and therefore reduce heat buildup. You definitely have passenger car tires. Trailer tires are designated "ST".

 

[summerwind1991]

Re: Tire Size Assistance

The boat had been bouncing, quite a bit, and I was tipped off in this thread. Thanks.

 

[summerwind1991]

Re: Tire Size Assistance

Thought there was a thank you thread in this forum. Anyway. thanks Again upinsmoke!

 

[summerwind1991]

Re: Tire Size Assistance

Getting a couple of different messages from a couple of trailer and tire dealers. One thought it really was not that big a deal to use Car tires, other thought they should be switched out for ST vs P. Any thougts, trailer is 17', boat is about 2300lbs fully loaded.

 

[Dunaruna]

Re: Tire Size Assistance

The dealer who told you that using 'P' is o/k - is an idiot, he doesn't know what he is talking about.<br /><br />Trailer tire (ST) have many different features when compared to passenger tires (P), not the least of which is stiffer sidewalls. Trailers don't have the same cushion ride of a car, stiffer sidewalls reduce swaying.

 

[summerwind1991]

Re: Tire Size Assistance

Thanks guys. I'm looking forward to a new set of ST and not so much bouncing.