Spare tire load range

catfish58 · Aug 6, 2012

I was preparing my car for a 300 mile trip and while checking tire pressure I thought while I had the compressor out I would check all my tires(boat trailer,utility trailer,truck,etc.). The boat trailer tires are Loadstar K550 with a load range C and max 50 PSI. The pressure was good but the spare had 35 PSI. Thats when I noticed the spare was load range B with max pressure of 35. How serious would this be in the event I had a flat and needed to use the spare? I just tow about 8 miles each way to the ramp and back. The spare has never been used. Thanks in advance.

Andy

MH Hawker · Aug 6, 2012

Re: Spare tire load range

It would most likely get you home on a short trip but I wouldnt trust it on any sort of a long trip.

catfish58 · Aug 6, 2012

Re: Spare tire load range

MH Hawker said:
It would most likely get you home on a short trip but I wouldnt trust it on any sort of a long trip.

Thanks a bunch. I'd hate to replace a new tire with a new tire. When I bought the boat I talked the dealer into giving me a spare after the deal was made.

Silly Seville · Aug 6, 2012

Re: Spare tire load range

The real truth to be discovered here, is not so much about the load rating, but how OLD that spare is? Trailer tires are notorious for failing due to non-use, not wear. And age coupled with non-use will destroy a tire in short order. So you may survive a lower load rating for miles and miles on a new tire, but suffer catastrophic failure while traveling a short distance on an old shriveled up correctly rated tire. YMMV!

catfish58 · Aug 6, 2012

Re: Spare tire load range

If I towed 20 or 30 miles each time I would go ahead and replace all of them. Besides,there's a tire store about 1 mile from the ramp.

Silvertip · Aug 6, 2012

Re: Spare tire load range

Nobody can provide a positive answer to your question because nobody knows what the weight of the boat, trailer and all of the stuff in the boat nor what size tires the tires are. If that weight is at, near, or over the load rating of the tires on the trailer, then the spare is clearly under rated for that load. If the total load is much less than the load rating of the tires then there is no issue.

catfish58 · Aug 6, 2012

Re: Spare tire load range

I don't know the weight of the trailer but it is a Karavan trailer rated for 2200 lbs. Tire size is ST 175/80 D 13. 75 4 stroke merc =385 lbs. Lowe FM165 hull wt=955. 3 batteries=150 lbs. Fuel capacity=27 gal but I usually tow with about 1/2 tank gas or less.That's about 80 lbs. High estimate for cooler,tackle,rods,trolling motor ect=300 lbs. Total weight would be approx. 1870 =plus weight of trailer. The tires on the ground(load range C) have a max load of 1360 lbs each. The spare(load range B)has a max load of 1100.

oldjeep · Aug 6, 2012

Re: Spare tire load range

New c rated tire rim is pretty cheap - around $100. Short trip at low speed it should get you home, but then you have to buy the correct tire anyways.

BoatDrinksQ5 · Aug 6, 2012

Re: Spare tire load range

I wouldn't sweat it at all! You were given that tire because that is what the capacity of the trailer is.... its cutting it close - maybe a hair over...

And just like car spares - i would keep the speed on it closer to 55 instead of 65. Also if on spare you could most likely off load some of your weight into the car and/or move some load closer to hitch.

But i would definitely replace it earlier then maybe you normally would. Maybe around 5-7yrs...?

Depending on size it is going to run 100-150 for a new tire/rim. Recently ran into an issue with mine where the tires are a little odd sized and ran 150$ for spare not the typical (89-110$).

catfish58 · Aug 6, 2012

Re: Spare tire load range

My towing speed is 45 to 50 mph max. I haven't had any issues with tires yet so I think I'll be ok until spring. I plan to replace them then anyway. Maybe I can find a used C rated rim this winter. Besides, most boat trailers I see don't even have a spare.

oldjeep · Aug 6, 2012

Re: Spare tire load range

catfish58 said:
My towing speed is 45 to 50 mph max. I haven't had any issues with tires yet so I think I'll be ok until spring. I plan to replace them then anyway. Maybe I can find a used C rated rim this winter. Besides, most boat trailers I see don't even have a spare.

Those are the guys you see on the side of the road trying to figure out where they are going to buy a tire on a sunday morning

I blew a tire off my car hauler at 3AM on a sunday in the middle of nowhere a few years ago. State trooper pulls up within about 15 minutes and was shocked to see that I not only had a spare but the tools to put it on.

Outsider · Aug 6, 2012

Re: Spare tire load range

- i would keep the speed on it closer to 55 instead of 65.

I think I'd keep it closer to 35, that's what he said the tire is rated for ...

catfish58 · Aug 6, 2012

Re: Spare tire load range

oldjeep said:
Those are the guys you see on the side of the road trying to figure out where they are going to buy a tire on a sunday morning I blew a tire off my car hauler at 3AM on a sunday in the middle of nowhere a few years ago. State trooper pulls up within about 15 minutes and was shocked to see that I not only had a spare but the tools to put it on.

Yeah, on 4th of July I stopped to render assistance to a young couple with a flat on their boat trailer. He had no spare and no jack. They were on their way to watch the fireworks at Point Mallard Park from the river. He had already called for a roll back. The wife was whining about missing the fireworks while he was complaining about the cost of the tow and replacing ONE tire. The other tire was in such bad shape I wouldn't even use it in a wheelbarrow.LOL

catfish58 · Aug 6, 2012

Re: Spare tire load range

If I need to use the spare you can bet everyone will be passing me. I'll hog the rght lane.

EDIT: I ment to reply 'with quote' to Outsider.

Silvertip · Aug 6, 2012

Re: Spare tire load range

Rims have a maximum load rating so you won't see a 13 inch rim with a couple different ratings. Using the numbers you provided you can add at least 600# for the trailer so you are 2500# give or take a tad. That is within 100# of the maximum loading for the current tires and 200# over the rating for the spare. Here's a workable plan, keep the best of the two current tires for a spare and buy two new tires rather than three. Again -- you don't need a new rim. Lastly, check the capacity tag on the trailer again. If the tag provides a GVWR rating of 2200# you are grossly overloaded. If it says LOAD CAPACITY 2200# with the tire size you currently have then you are still at the load limit. GVWR is Gross Vehicle Weight Rating and includes the weight of the trailer, the boat and everything in it. Boat weights are normally dry weight and don't include batteries, fuel, accessories and the ton of other stuff thrown in. The reasons for trailer tire failures are as follows (in approximate order).

1) Low inflation pressure
2) Overloaded (Exceeding GVWR)
3) Overloaded (wrong tire size for GVWR)
4) Age/rot
5) Alignment

catfish58 · Aug 6, 2012

Re: Spare tire load range

Silvertip said:
Rims have a maximum load rating so you won't see a 13 inch rim with a couple different ratings. Using the numbers you provided you can add at least 600# for the trailer so you are 2500# give or take a tad. That is within 100# of the maximum loading for the current tires and 200# over the rating for the spare. Here's a workable plan, keep the best of the two current tires for a spare and buy two new tires rather than three. Again -- you don't need a new rim. Lastly, check the capacity tag on the trailer again. If the tag provides a GVWR rating of 2200# you are grossly overloaded. If it says LOAD CAPACITY 2200# with the tire size you currently have then you are still at the load limit. GVWR is Gross Vehicle Weight Rating and includes the weight of the trailer, the boat and everything in it. Boat weights are normally dry weight and don't include batteries, fuel, accessories and the ton of other stuff thrown in. The reasons for trailer tire failures are as follows (in approximate order).

1) Low inflation pressure
2) Overloaded (Exceeding GVWR)
3) Overloaded (wrong tire size for GVWR)
4) Age/rot
5) Alignment

The tag on the trailer says Load Capacity 2200#. As stated earlier I will be replacing 2 tires next spring,unless I have problems beforehand. Since I won't be needing another rim I'll use one of the C load capacity tires as a spare. I will be looking into pricing Load Capacity D tires as well,if they are not to cost prohibitive.
Thanks Silvertip.

Andy

Captain Caveman · Aug 6, 2012

Re: Spare tire load range

I've always felt that a fella could make good bar change by rolling around the popular highways with a spare trailer tire/rim.

oldjeep · Aug 6, 2012

Re: Spare tire load range

Captain Caveman said:
I've always felt that a fella could make good bar change by rolling around the popular highways with a spare trailer tire/rim.

And you would only need to do it for the 3 big weekends in the summer Memorial, 4th and labor day to get most of the un prepared

Spare tire load range

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