Technical Space saver spare for the 55?

My 55 is a true daily driver and has been for the past 39 years. As such, the trunk is actually used daily to haul anything an everything. I narrowed the rear and tubbed it about 15 yrs ago which required deleting the spare tire trough. Since then, my full size spare has been ****ing up valuable trunk space. As a daily driver it is only logical to carry a spare and jack.
So.... I'm working toward using a space saver spare. I found one with a compatible lug pattern (4.75x5) in a 90s Camaro. The temp tire is T135 / 60R16. I did a test fit on the 55 and lol...that baby gets lost in the cavern. It looks scary small. My rear tires are P295 / 50R15 so thats a significant down size.
I can grab a taller temp tire and put it on this compatible rim if necessary, but my questions are this:
Is this tiny tire safe at 45-50 mph?
Should I up size to a taller tire?
The "tiny" spare sure looks good in the trunk.

 

A space saver is there to get you out of a pinch, not for driving at highway speeds.

I cut a tire on my early 90s Crown Vic daily driver on the Interstate when I was going to college and I only drove about 30 or 35 to get to the closest tire shop!

 

It will get you off the road

 

LOL.. you are making me remember an old memory... I'm to understand those space savers were only meant to get you somewhere safely as a temporary measure to have your flat tire repaired or replaced. Many moons ago, when I was in college there was a foreign student who lived in my neighborhood who drove a super inexpensive, battered used car, with those safety spares on all four corners, year round!

 

60 profile is very small for a space saver

I use a 145/90 16 as fitted to a chrysler grand voyager as a space saver. Its about 27" diameter.

 

How many times have you used the spare in the past 39 years? I think I used the spare once on my 55, I had the car 20 years, and put almost 100k miles on it. But I also ran some old Radial TA tires for a while, and that was the problem.

Keeping the tires maintained goes a long ways towards not needing a spare, Keeping a plug kit and compressor can also be a big help, that's been my plan of attack more recently on most of my cars.

If you have an open differential, the small tire probably won't hurt anything, but who has an open diff on a tubbed car?

 

Do you have a posi or similar? Don't run different tire sizes on the rear
Edit, Ha, Jim beat me to it.

 

Had a friend run a space saver spare on his rod for 150 miles at highway speed. I would not do that but he did with no problem.

 

Match the spare tire's O.D. to you current rear tire's O.D.

By the time all is said and done, you might be better off keeping a full size spare tire. You're going to gain a few inches in either direction around the spare by going to a space saver, but you need to make sure the used space saver you buy is safe and reliable...not many people check and keep their donut spare properly inflated, but on the plus side, they do stay out of the weather, so the rubber is usually still in good nick.

FYI, '82+ Camaro/Firebird wheels will have high positive offset. Chevy/GMC 2WD (not 4WD) S-series pickups and Blazer/Jimmy have the 5x4.75 pattern, more RWD friendly offsets, and if you get lucky and find a 2WD Blazer/Jimmy, the full size spare is often stowed inside. out of the weather.

Alternatively, have an older, narrow (5") steel wheel fitted with a narrow radial tire, then use that as a spare.

 

Damn.. didn't factor in the posi. I need to rethink once again.

 

…hmmm. Now hang on a sec. If each tire is rolling at the same rpm as the posi drives the axles equally,tire size should not be an issue...I think...? Head scratching.

 

Your P295/50/15 is 27.7 inches tall, you could carry a P215/75/15 spare on a narrow rim, also 27.7 inches tall.

 

It'll work, it just will be putting excess wear (and heat) on the posi, like you're going around a turn all the time. The clutches will have to be slipping to let the tires turn at their different speeds, due to the tires traveling different distances for one complete revolution.

 

Convert to utility sedan interior.

 

That's exactly the problem, because of two different tire diameters the posi will be slipping when it normally wouldn't be. The axles will be at different speeds because the outer cir***ference of each tire will be at a different speed.

 

This. A narrower tire that is equal in height to your rear tires on say a 6" wide wheel will allow you to go a long ways in the case of a flat, and you should be able to use it on all four corners.

 

Yours is over 2" difference....
Use this website:
https://tiresize.com/comparison/

Look for the same or close in o.d. A T135/90D17 is the same size. Or just get a T155/90D16 tire to replace the smaller tire on the temp wheel (new or junkyard).

Tire sizes here:
https://tiresize.com/tires/Goodyear/Convenience-Spare.htm
Then all that's left is finding a new car with your bolt pattern and then head to the junkyard or online.

I have them in a few cars, the only one I had to mess with is one of the Hillmans. I had to buy 2 at the wrecking yard and swap tires to get the size I needed......but I ended up selling the one I didn't need so it all worked out. For the '41 p/u I just bought a new tire the size I needed and put it on a '40 wheel.

 

I think my brain cloud is clearing . Think of a cone rolling on its side. One big end and one small end. It would never roll straight ahead and always want to push into a curve.

 

Yeah. Your regular 27" tire based on cir***ference will travel roughly 86 inches per full revolution. Your 22" space saver will only want to travel 70 inches during the same single revolution. The Posi will be unhappy.

 

Yes, so in the case of a differential, the smaller tire has to turn faster than the taller tire for the car to go straight. Therefore the shorter tire's axle has to turn faster, and on a posi that means the clutches have to be continually slipping.

 

Consider the Lo-riders. No, don't.

 

When considering a spare, especially a space saver, your front tire cir***ference should be factored in also. You don't have a crystal ball to let you know which tire will go flat first.
The fact that you have tubs indicates you are running "bigs-n-littles" but if the cir***ference of the fronts is less (shorter) not just less wide, you may want to consider a spare cir***ference somewhere in between. A million cars have gotten home on those short spares, but the closer the spare cir***ference is to whatever tire is replaced to limp home, the longer the trip can be with less white knuckles.

 

You're better off to run a spare that is the same height as your rear tire, if it will fit and be drivable on the front. For the OP, looks like he has fender well clearance on the front so it might work for him.

 

No, its called tire stagger that's way oval track cars (spools) run a larger tire on the right rear then the left rear

 

So, what I would do is when getting a flat in the rear. Take the tire off the front and switch it to the rear. Then put you space saver on the front. Problem solved. I try to put space savers in vehicles I work on for people. Having them is better than not having one at all. I hve used more than a couple Chevy Mini vans spares. They are good and tall.

 

That could work, but not with a mismatch in tire height. He’d probably be still running a smaller tire on the rear, putting wear on the posi unit.

 

But it would be better than the spacesaver he has now.

 

Like Squirrel said plug kit and compressor. By the time you get the correct diameter space saver spare all you are saving is the width of the tire in the trunk. Or AAA and a roll back.

 

And now for my closing statement:
First of all, thanks for all the impressive insight on this topic. Makes me think some of you guys actually know what you're talking about..lol.
I'm going a dual route. I like the idea about keeping a small compressor and tire kit handy, so I'll definitely do that. It takes very little room for the peace of mind it delivers.
Secondly, my rear tire is a 26.6" diameter and the front is 26.1. A common spare available in the local yards is a 145/90R16 which is a 26.3 diameter. I'll snag one next trip to the yard and mount it on my 16" space saver rim.
Now I can toss it in ( or not) when I feel the need and also have a means of roadside repair handy.
Also been pondering why I feel the need. I guess I grew up where being self reliant was the norm. Remote roads, no cell phones, and vehicles not nearly as reliable as the newbies. Personally...I like those days better. Just saying...

 

I carry a spare (some temps) because I like to drive at night, push my luck (ahhh, that tire still has tread on it), don't like relying on a tow truck (the only time I used one is to get 1 car home after I bought it). Tools, spare and gas can in all vehicles....the tire plugs on long trips only.