Spare tire smaller than the tires on the truck?

[Explorerinil]

What about ABS brakes, stability control and possibly traction control issues with a different sized tire on your 19 ram?

 

[rayra]

OP's plan will work. I prefer a matching spare myself, so that my only inconvenience is needing to change the flat.

 

[billiebob]

A 37 will not fit in the spare location on a Ram.

It’s really not dangerous to run a different tire.

Like I said I wouldn’t do it for long or at high speed, but differentials are literally designed to spin axle shafts at different speeds. Why do you think your tires don’t chirp around corners? The inside tire will always spin at a slower speed than the outside tire.

The number of people that don’t get that is astounding.

Don’t run it on the rear, or in 4 wheel drive and you’ll be fine.


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Cannot agree, do some research with your local vehicle regulations, I'll bet you will find a law saying you cannot do it.
Why did you ask the question if your mind was made up?

 

[Tudor Tanase]

On the back, it may damage your diff. On the front it‘ll pull to a side, potentially very hard. Not sure your power steer will like that. Id say put it on the front and drive around the block, carefully. Then think if you want to do that for greater distance and/or speed.

 

[Winterpeg]

What happens if you are in an offroad situation and slice a sidewall (get a flat).... and need every tool at your disposal to get out of the situation? Including full size proper offroad tires?

I carry a fire extinguisher too.... I prefer to have and not need rather than the reverse.
(side note: I've used that extinguisher 3 times now to help others)

 

[jadmt]

Cannot agree, do some research with your local vehicle regulations, I'll bet you will find a law saying you cannot do it.
Why did you ask the question if your mind was made up?

Considering there is no law that says you can not run a donut spare doubt you will find much in that regard. If there is it wont be enforced.

 

[ttengineer]

Cannot agree, do some research with your local vehicle regulations, I'll bet you will find a law saying you cannot do it.
Why did you ask the question if your mind was made up?

I think you have me confused with the OP.

In an emergency I also wouldn’t be concerned with senseless DOT and/or government regulations.

Most states have laws about modifying/lifting your suspension as well, but we don’t pay any attention to them.


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[nitro_rat]

I usually let the largest stowable spare tire size dictate the tire size I run on the vehicle. I avoid some vehicles because it's not possible to stow a matching spare.

A deflated 35 may be the largest tire you can stow on a Ram. It may be a good compromise for you. It just depends on what you are personally comfortable with...

 

[Capital E]

I'm really not worried about the legality of it. I understand it's not ideal. In 25 years I have had one flat tire. I carry a patch/plug kit. I also carry a fire extinguisher even though I've never needed it. A fire extinguisher weighs a couple pounds and can be stowed under a seat. A 37" spare is roughly 130 pounds and takes up quite a bit of real estate. I just don't like the idea of lugging that around with such low odds of needing it. The chance of getting a flat that is not repairable is pretty slim but it's possible which is why I ask. I'm more concerned about any mechanical damage or messing up the electronics in the off chance that the worst happens. This would be low speeds and short distances, just like driving on a donut in a car.

 

[mep1811]

I think I missed the tire size difference. I would not do it.
I think any damage that could be done would be more expensive than the cost of the proper sized tire.

 

[Betarocker]

With modern vehicle, you run the risk of screwing up the signals to the PCM .

 

[jadmt]

People have run different spares from the beginning of time. locally it would not bother me. On a long road trip my only reservation would be if you destroyed a tire so bad it could not be repaired and you could not find a replacement.

 

[Explorerinil]

With modern vehicle, you run the risk of screwing up the signals to the PCM .

Yes like I mentioned, the ABS system, vehicle stability control... it will throw codes.

 

[alanymarce]

re "I carry a fire extinguisher too.... I prefer to have and not need rather than the reverse."

We carry two - here it's a legal requirement - so if you ever use it you're no longer complying with the law unless you carry two...

 

[jonathon]

I think a 35” spare can be stored in the stock location. 37’s look cooler but I’m not sure there is a functional difference other than an inch of ground clearance for the axles and more rubber to turn.