Tire size, Old vs New

[Condor1970]

I have an old set of tires on my trailer from the 80's. Size F78-14ST. Now, the modern day equivalent is supposedly 205/75R-14.

so, my question is. Since my spare is in like new condition, but the old size, and the 205's are new. Can I keep/use the old F78 spare? Will it work ok with the 205's if I need it.

 

[dingbat]

Tires have a life expectancy of 6 years from date of manufacture. A 1980's tire is a bit beyond that limit. Toss it and buy a news one, for safety sake

 

[GA_Boater]

Wow - At least 25 years old. The spare, while looking OK now and holding air, might give up the ghost when you put it on the trailer and put weight on it. If you're lucky the Admiral is sitting at home waiting for you and the rain isn't too wet while you're changing tires.

I would buy new tires including the spare, if only for peace of mind.

 

[H20Rat]

Old tires last alot longer than new ones... I have 20+ year old tires that still look to be in fairly decent shape and get used often. Any trailer tire that I've bought in the last 5 years starts degrading almost immediately, and in some cases, I'm lucky to get 2-3 years out of them before they are so weather checked they aren't safe. (smaller the tire, the worse it tends to be for some reason.)

 

[Starcraft5834]

Tires have a life expectancy of 6 years from date of manufacture. A 1980's tire is a bit beyond that limit. Toss it and buy a news one, for safety sake

+1 get rid of those old tires......tractor supply,, tire on the rim for about a hundie........

 

[drrpm]

Beyond the age, bias and radial tires should not be used together.

 

[haulnazz15]

Beyond the age, bias and radial tires should not be used together.

I have never seen any definitive proof to support that old-wives tale. Sure, you don't want to use them on the same axle any more than you'd want two different sizes of radials or two different brands on the same axle. However, if one axle has radials and the other axle has bias-ply, you won't be able to tell the difference.

 

[kjsAZ]

simpletire.com or wheelsexpress.com have really good prices for tires. Get a radial as they handle better and develop less flat spots when parked longer. As it was said above trailer tires don't die from wear but age and the usual recommendation is to change after 4-5 years. Depends a bit on how much sun and heat they get during that time. If stored cold and dark they make it a bit longer.

 

[Mel Taylor]

Way back in the early 1970's I had a chevy panel wagon with a set of borrowed Michelin radials on the rear and bias ply tires on the front, or vice versa (as I said it was the early 70s) it drove fine until I made a trip through some mountains on a narrow, winding highway with no shoulders to speak of. If I remember correctly, I would turn the steering wheel going into a curve and nothing much would happen at first then suddenly the vehicle would over steer (if that's the correct term) and I would find myself frantically turning the wheel back to avoid going off the road. I made that same trip four times over a two week period before I got the money to replace the radials with bias ply tires. Bias ply because I couldn't afford radials which were not so widely available then and much more expensive than bias ply tires. I've no idea how mixing radials and bias ply tires would affect a boat trailer.

 

[smokeonthewater]

Yep I have first hand experience with mixed bias and radial on a vehicle..... Front n rear... One way will make it under steer ie drive off the road in a curve and the other will make it over steer ie spin out in a curve... WAY bad news.... With that said, on the same a le and on a trailer it wouldn't make much difference... Might sway a little more one way than the other but since the tires are on the same axle one can't steer the other... With THAT being said... That spare is way way way past it's usefull life... Toss it.