Tire Size Problem.

[Sammy-56]

I have a 1990 18.4 Grumman on a Shorelander Trailer with a 90hp Force and I bought it brand new and it had A78-13 ST on it and I had to replace them for they were shot. Couldn't find A78-13 and the ST165/80D13 which is supposed to be the cross reference which is still out there but hard to find only found them on the internet. Local dealers are telling me that they can't get the 165/80D13ST either and that I should go to the ST175/80D13 because they are and will be easy to get down the road. So I did and I had to use a screwdriver to help get it past the fender in order to get it on. Tire is hitting on both sides of the fender and hardly no clearance on top. So I thought of putting a 1" steel block in to drop axel down but I think that will give me clearance at the top and I can roll down the road with it but if i need to change a tire out I think it will still be a tight fit on the sides of the fenders getting the tire on and off. At this point I don't know what to do should I change the fenders or try to get 165's or what? Thanks hope someone can lead me in the right direction.

 

[goegr]

Re: Tire Size Problem.

I would adjust my fenders and stick with the tires you have just bought. They're paid for and you will have an easier time buying a tire if you have to replace one.

Good Luck!

 

[Silvertip]

Re: Tire Size Problem.

The reason the tires you are looking for are hard to find is that they are bias ply tires. Radials are much more common these days and are simply a better tire.

 

[Sammy-56]

Re: Tire Size Problem.

I would adjust my fenders and stick with the tires you have just bought. They're paid for and you will have an easier time buying a tire if you have to replace one.

Good Luck!

Thanks for your response I can't adjust the fenders all I can do is replace them or install a steel block shim on the axel to raise the fender heigth about an inch but the tire will still be a tight squeeze getting on and off.

 

[Sammy-56]

Re: Tire Size Problem.

The reason the tires you are looking for are hard to find is that they are bias ply tires. Radials are much more common these days and are simply a better tire.

Hi and thanks for your response the tires I installed are kenda loadstar
ST175/80R13. The radial ST165/80R13 I could not find anywhere local the only ones I found were on the internet and not available at this time a few of them said they might get more from overseas but could not give a time frame and the problem is I needed something on there right away for I have to bring the boat to have some work done. Thanks for your response

 

[Titanium48]

Re: Tire Size Problem.

Do you have brakes on your trailer? If not you could go with 12 inch wheels and ST145/R12 LRD tires. 1200 lb load rating and they will fit under the fenders easily (~1 inch smaller than stock). They won't fit over a 10 inch brake drum though.

 

[Jeep Man]

Re: Tire Size Problem.

This is considered taboo by some, but I am going to suggest a car tire. ST series tires are for trailers and have a heavier sidewall to increase stability for heavier loads or higher loads. I believe your boat is aluminium and therefore you MAY be well under the load limit. If this is so, and your boat is less than the car tire rating, many small imports use this size tire. SAFETY FIRST

 

[Titanium48]

Re: Tire Size Problem.

P165/80R13 used to be a reasonably common car tire size, but not so much any more. P175/70R13 is still pretty common though. Typical load index for P165/80R13 is 83 and for P175/70R13 is 82. Derating 10% for trailer service gives a load rating of 428 kg (941 lb) each for the P175/70R13 or 438 kg (965 lb) each for the P165/80R13. Something to consider if your boat + trailer are under 1800 lb or so.

 

[Al Kungel]

Re: Tire Size Problem.

Sammy-56,
I have a Shorelander trailer and when I went from 13" wheels to 14" wheels clearance became a problem. To solve the clearance issue I had some some blocks (1.75" x 1.75"x 4" solid stock) welded to the axle and got longer U-bolts to fastened the springs in place.

 

[Sammy-56]

Re: Tire Size Problem.

Thank you AL for your response I'm actually staying with the 13" tire going from A78-13 at 22.50 diameter to ST 175/80R13 24.00 diameter which makes it 1.50 bigger in diameter. My trailer weighs 370# aluminum boat weighs 870# and the 90HP force weighs about 300# total 1540# not including gas and gear. Seems if I raise the springs up with lets say a 2" block I'll have clearance above the tire but the tire will still hit the sides of the fender when changing out the tire. Right now I have 9 inch high fenders leaving me with 3/4 of an inch clearance to the boat, next size up in the fender is 12 inches in heigth meaning that it will hit the boat. The boat trailer came new with the A78-13s on it 1215# max load and the boat and motor described above. So this trailer was matched up with this boat. I called shorelandr and they told me that the only thing I could do is put 5.30x12s on it but I would be loosing 170# and trailer would sit closer to the ground and that they weren't telling me what to do that it was my call. At this point I don't know what to do. Was your situation similar to mine? I don't know if it will be safe to downsize the tire.

 

[Titanium48]

Re: Tire Size Problem.

If you want to use 12 inch wheels without reducing the load rating you need to get load range D tires. 5.30-12 (bias ply) often only come in load range C (1050 lbs), but the same size radial (ST145/R12) can easily be found in load range D (1220 lbs). If you don't have 10 inch brakes to worry about I'd go with the ST145/R12. If you really want to raise your trailer (can't see why you would though), keep the ST175/80R13 and use spacers at either the axle or the spring hangers.

 

[Wee Hooker]

Re: Tire Size Problem.

If they are already hitting ( or near hitting) I'd think that you're going to need closer to a 2" spacer/block. That said, I think I'd cut my losses , and go the simple route. i.e. I'd sell those tires and rims and buy a new set of wheels (12x5.30's). Won't cost much more than the trailer mod in the end and you'll have a easy to find/standard size. You'll also retain your same boat launch depth vs needing 2" more water.

 

[TexasBayFisher]

Re: Tire Size Problem.

If you can't find the tires you can get used trailer wheels/tires for about $40/piece.