increasing tire size no reason, just piece of mind

[rothfm]

Another tire question.....

My 21 open fish+ski is matched to its trailer, no issues towing. I need to replace its F78-14 ST tires load Cap "C". Was wondering if there is any benefit to going to a 15' tire load C or D. No particular reason, other than a maybe a beefier, more durable tire?? I'd have to change Rims obviously and maybe the Fenders.

 

[QC]

Re: increasing tire size no reason, just piece of mind

The best thing you can do is get another set of 14s, keep them covered, keep the trailer on jacks, and inflate them to near their max when you are towing. Unless the 14s are underrated I don't see any reason to go to the 15s . . . I think that is now a ST205/75D, C rating is 1760 lbs each.

 

[tashasdaddy]

Re: increasing tire size no reason, just piece of mind

unless you are towing the Queen Mary, the 14's should do fine. a lot of gas can be bought, for what the changes would cost you. some companies do make a "D" rated 14.

 

[dingbat]

Re: increasing tire size no reason, just piece of mind

A tire is rated significantly lower than its design load. You would be doing nothing more than further padding an already significantly large margin of error

 

[Silvertip]

Re: increasing tire size no reason, just piece of mind

I feel there is not as much safety margin here has one might think. 1760 x 2 = 3520# max load. Consider the trailer weight 500 - 600#, add the boat, add the engine, add the fuel, add the battery(s), add gear, and the combined weight would very likely approach that limit. Banking on a safety margin whether it's tires, or bridges is never a good idea. Anyone remember the I-35 bridge incident in Minneapolis?

 

[NYBo]

Re: increasing tire size no reason, just piece of mind

Sometimes, bigger IS better. Just make sure your trailer remains level. It will be slightly higher if you end up with larger diameter tires.

 

[QC]

Re: increasing tire size no reason, just piece of mind

I guess I was assuming a tandem axle trailer . . Do we know?

 

[Silvertip]

Re: increasing tire size no reason, just piece of mind

Dang -- I hate when assumptions bite me. If this is a tandem there is no tire issue. If it is a single axle tailer, there might be.

 

[QC]

Re: increasing tire size no reason, just piece of mind

Agree 100% with all ^^^^

 

[freddyray21]

Re: increasing tire size no reason, just piece of mind

Another tire question.....

My 21 open fish+ski is matched to its trailer, no issues towing. I need to replace its F78-14 ST tires load Cap "C". Was wondering if there is any benefit to going to a 15' tire load C or D. No particular reason, other than a maybe a beefier, more durable tire?? I'd have to change Rims obviously and maybe the Fenders.

I haven't heard of an F size tire since I was a teenager. If they lasted that long then I would put the same size back on.

 

[rothfm]

Re: increasing tire size no reason, just piece of mind

Thanks for the input everyone...Sorry, its a single axle. Tires are just old and I want new ones. I'm approaching trailer max with boat loaded, including fuel. The F78-14ST's are indeed 205/75d-14 1760 weight cap. There is a G78-14ST which is 215/75D-14. Its specs are 1820 I believe-Not alot of difference until one gets to the 15's. I"m assuming the G78-14's will fit my rims, but not sure. Just figured if I'm replacing I can get a bit of a beefier tire, especially if remaining at 14".

 

[Titanium48]

Re: increasing tire size no reason, just piece of mind

I'd go with the ST215/75D14 (bias) or ST215/75R14 (radial) LRC. They'll give you another 110 lb of load rating each (1870 lb instead of 1760 lb) and will fit your existing rims. It's also highly unlikely you'll require any fender modifications with these.

I suspect that your weakest link is your axle - 3500 lb is a common axle rating. The 1870 lb tire load rating would thus provide an extra margin of safety but there isn't much point in increasing it any further.

 

[reelfishin]

Re: increasing tire size no reason, just piece of mind

Keep in mind something else, the ride height of the boat will be increased, which can make a big difference when launching and loading.
On my 14' aluminum boat, it came to me with a tiny 8" tire trailer, but the trailer was narrow and the boat sat over the tires, I switched it to a wider, 13" tire trailer which lets the boat set much lower, thus I don't have to take my truck swimming everytime I load the boat. I could even go to 12" tires to get it even a bit lower but it's already 7" lower on the new trailer, and I don't have to worry about bearing or tire failure at highway speeds.

Also, larger tires cost more money, why spend more than you need to, especially since most trailer tires generally dry rot away long before they wear out.

 

[mthieme]

Re: increasing tire size no reason, just piece of mind

For some reason, it's easier to find 14" trailer tires than 15's in my area.
I have both sizes - along with 12" and 8".

 

[Floatsum]

Re: increasing tire size no reason, just piece of mind

I feel there is not as much safety margin here has one might think. 1760 x 2 = 3520# max load. Consider the trailer weight 500 - 600#, add the boat, add the engine, add the fuel, add the battery(s), add gear, and the combined weight would very likely approach that limit. Banking on a safety margin whether it's tires, or bridges is never a good idea. Anyone remember the I-35 bridge incident in Minneapolis?

As you stated,,,
Now add a tight turn shifting weight more to one tire,,,
and hitting a pothole in the turn.
Not too hard testing the true rating when you think of it.

 

[reelfishin]

Re: increasing tire size no reason, just piece of mind

For some reason, it's easier to find 14" trailer tires than 15's in my area.
I have both sizes - along with 12" and 8".

I have the opposite here, I can buy 8, 12, and 15" trailer wheels and tires just about anywhere, but no one carries 13 and 14". The last time I needed 13" I had order a bundle of 10 wheels and tires.
I've tried to keep all of my trailers with the same size wheel and tire, most all use 13". For both convenience and height reasons. None of my boats need even the carrying capacity of even the 13" tires so weight carrying capacity isn't an issue for me here.