There is a speed limitation to limit the possibilities of weird handling characteristics and grip during turns creating accidents, but I've never seen total distance limits.
These aren't good mpg tires. I did some roll-down distances tests with a set of four while preparing for the 2005 Tour de Sol event.
They are just not large enough to carry the load without a lot of RR-inducing sidewall deflection. That's why they require so much air pressure, but it's still not enough. This is a demonstration of the theory that wider tires have less RR than narrow ones...they are very narrow.
Originally Posted by BEEF
I have heard that the "doughnut" tires as I have heard them referred to should only be traveled on 50 miles at no more than 50 MPH.
Most are marked with their limits...if they don't have a specific distance limit then I wouldn't worry about the tire -- though you may want to check the car's manual for a distance limit to quit worrying about the differential.
one idea (just an idea) maybe it is a limited trip amount. maybe it can't take the heat of traveling that fast for that long. [...] it makes more sense if it were limited in a single trip how far it can go.
That matches up with the RR and sidewall deflection issues.
just a thought, you could replace the entire axle. that way you would know what it was. maybe talk to a junk yard before you pull the axle as far as pricing and tell them you want to do it cheap and what you are using it for. they may hook you up. we have these places around here U-PULL-IT and they are reasonable but as the name states. you have to pull whatever it is off of the vehicle so it may take the better part of a day.
as for the tongue, can't you weld it back? I know, that isn't the point.
Be the change you wish to see in the world
Yeah, I was thinking of just replacing the whole axle with a proper trailer axle. That would cure every one of my problems. I figure I could get a totally rusted out trailer with a reasonable axle for near nothing.
Another option would be a junkyard car axle, the rear axle from an older FWD car might do the job (I remember the axle on my '97 Grand Am went all the way across with a simple beam). Most (maybe all) junkyards around here are full-service only (they call themselves "used auto parts" businesses) and won't allow you to pull your parts or even walk into the junkyard area. Anyway, if I got one, I would then know what compact spares to get!
I can't weld it because I'm neither equipped nor trained for welding. Some day I will get appropriate equipment. Any recommendations for a shoestring budget welding setup? (I know, not likely.)
before I even say this, it is very BUBBA-engineering but...
you could go to lowes and get some metal straps, drill some holes in both pieces and bolt it back together. using locktite on the bolts so they don't come undone. maybe even paint it so it doesn't rust again.
that is instead of getting a small welder. given the tongue weight of that traier (just by the looks) you may not have any problems just strapping it together. I would use several straps though and as heavy duty as I could buy.
*edit* another consideration for an axle is maybe a small car that was rear wheel drive like a chevette or something. gears shouldn't matter, you will have your solid axle and the small tires you want. just a thought.
Be the change you wish to see in the world
I wasn't going to admit it, but yes, splicing it with additional metal was the most likely solution I was going to use. I have some nice angle iron that would be perfect. The tongue, and the whole trailer completely loaded, is very light indeed; I lift the tongue by hand, and I can even lift either rear corner by hand. Those huge tires actually cause the whole thing to float without the boat, motor, and two batteries on it (with the batteries in the rear). That's another reason I want less tire, so it doesn't float.
Good point about the RWD axle working also. It ought to be easier to find that a beam rear axle from a FWD.
Oh, one additional addtional thought on bolt circle: Considering that it came with SUV tires on it, I took that as confirmation of my bolt circle measurement and vehicle match.
When I bought a set of (5) VX rims for my '91 Civic, I took a closer look at the factory spare. It had the same height and weight as my factory steelies. So even if you could ride on four "space savers", you might get better FE with a lighter wheel/tire combination.
Outside diameter of the tire is often different, which is definitely bad for the differential.
Really, though, the main reason it says not to drive them far is that they are not designed for general purpose driving. They are narrow, low profile, high pressure, low capacity, with tread that is not designed for great traction or long life. They were designed to be inexpensive, lightweight, and compact; and to get those qualities, they compromised other abilities.
I'd like to use a couple for my boat trailer, which was homemade (by someone else) and carries very little weight on currently huge tires, too high for easy loading of the boat. I can't seem to figure out my bolt circle correctly; I though I measured and calculated it perfectly but the wheel I bought didn't fit right.
You should be able to figure out the bolt pattern by measuring center to center of two holes that are side by side and then check 2 holes on a diagonal center to center, then just find a wheel with the same dimensions.
Those huge tires actually cause the whole thing to float without the boat, motor, and two batteries on it (with the batteries in the rear). That's another reason I want less tire, so it doesn't float.
But consider the time savings by just unplugging the wiring at the launch ramp! Use aluminum bolts for the tongue splice, back down quickly, slam on the brakes and the bolts shear letting the boat and trailer remain together. I'll wager the tires add some pontoon-like stability to minimize tipping: flotation when submerged, down rigger when lifted up above the surface.
i certainly drive more than most, but i can't give a tech reason supporting undersized spare's limitations. instead allow me to site a common sense observation:
i've see an uncountable amount of vehicles abandoned with a small blown spare ON THE CAR. it's pretty simple...use the spare (undersized or not) to get where you're going, then repair/replace the original and put the spare back in the trunk!
upon seeing the frame I exclaimed "MODEL A FORD" what you have there is a modified front axle from an OLD car that has been cut and welded together to be narrower than original. I would recommend replacing it with something with a standard pattern and call it a day. and the tongue have a buddy who welds for a hobby/living do it that job would take 5 minutes and you'd be set.