Run Flat vs Second Spare Tire

[jtcawrse]

Hello.

I appreciate the vast amount of knowledge here on the forum and thank you in advance for your thoughtful input.

I am going to build an overland vehicle from the solid bones of an LMTV.

Most overlanders carry two spares on their adventures. This is because if you blow a tire and have to use your spare, well, then you no longer have a spare. Which is why you carry two.

My thought is to only carry a single spare and count on the run flat inserts to allow me to limp to help in a situation where my spare is no longer in play.

How feasible is this?

Are there downsides to running wheels with the run flat inserts?

Which run flat insert is preferred?

Thanks again for your insight.


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[NDT]

Runflats for 395s are a nightmare to get in and out of a tire. The military only used them on MRAPs that run 395s, so they are not common to find on the loose. If it were me I would carry tire tools so I could repair my own punctures.

 

[simp5782]

The composite runflats can be found for around $50 each and are simple to install not to mention alot lighter than rubber ones.

Carry two spares. Plug and patch unit or vulcanizing plug gun as well. Even if you limp back to safety 395s arent common everywhere to just pick one up.

 

[Awesomeness]

I wouldn't want to try to offroad out of a trail on just a runflat'd flat tire. So carrying 2 spares is still probably smart.

The 3-piece bolt-together "composite" runflats that Simp mentioned are easy to install and deal with. Downside to running them is they add non-trivial rotating mass, which means they are reducing gas mileage (by how much would be up for debate... maybe 1-2%?). Upside would be that in a rapid blowout that corner of the truck isn't going to drop as far, helping maintain control.

 

[jtcawrse]

Does driving on a run flat at limp speeds ruin the tire?

How far could you travel on the run flat assuming you are driving on a relatively flat dirt road or pavement?

What speed is safe?

I plan on carrying tire repair tools so really I’m just considering a nonrepairable sidewall blow out.

If I only carry one spare with run flats, once a tire has a hole in the sidewall, my fun adventure turns into a search for a new tire.

Hmm, 2 spares is such a huge amount of space and weight.

I really don’t like your answers

When replacing a tire in a foreign country, can they be found locally or would I likely need to import it?

Mostly thinking about North, Central, and South America.




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[NDT]

Haha 395s are EVERYWHERE in a few places like Texarkana, TX but OMG try to find one ANYWHERE ELSE and you will be in trouble.

 

[simp5782]

You only need one spare on a wheel really. If you screw up 2 wheels then you have issues anyways. You can use a + strap and secure a tire without a wheel to the one on a wheel on the truck.
Or strap it to the roof. One not on a wheel is not heavy and it would not be any taller than an ac unit on top of the truck. Then mount the heavier wheel spare for easier access.

 

[jtcawrse]

You only need one spare on a wheel really. If you screw up 2 wheels then you have issues anyways. You can use a + strap and secure a tire without a wheel to the one on a wheel on the truck.
Or strap it to the roof. One not on a wheel is not heavy and it would not be any taller than an ac unit on top of the truck. Then mount the heavier wheel spare for easier access.

So you’re saying 1 spare wheel, 2 spare tires.


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[coachgeo]

... One not on a wheel is not heavy...

how heavy do you find just tire is?

 

[simp5782]

how heavy do you find just tire is?

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[simp5782]

So you’re saying 1 spare wheel, 2 spare tires.


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Yes. Even a bald tire that holds air is better than a flat tire with a hole in the sidewall

 

[Curtisje]

Does driving on a run flat at limp speeds ruin the tire?

How far could you travel on the run flat assuming you are driving on a relatively flat dirt road or pavement?

What speed is safe?

I plan on carrying tire repair tools so really I’m just considering a nonrepairable sidewall blow out.

If I only carry one spare with run flats, once a tire has a hole in the sidewall, my fun adventure turns into a search for a new tire.

Hmm, 2 spares is such a huge amount of space and weight.

I really don’t like your answers

When replacing a tire in a foreign country, can they be found locally or would I likely need to import it?

Mostly thinking about North, Central, and South America.




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Driving on tun flats does ruin the tire. The military run flats usually advertise 30 to 40 miles at 30 to 40 mph. In my experience your lucky to get 20 miles at 10 mph out of them before they are shredded and fall off the rim, that is if they don't catch fire first.

 

[jwchameleoncorp]

What about carrying inner tubes? If the tire is punctured would an inner tube work? You could carry a box of them. They can be installed in the field. Maybe not even need a spare (although I'd still bring one.)

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[simp5782]

What about carrying inner tubes? If the tire is punctured would an inner tube work? You could carry a box of them. They can be installed in the field. Maybe not even need a spare (although I'd still bring one.)

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Wont work with the wheel

 

[jwchameleoncorp]

Wont work with the wheel

Why not?

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[simp5782]

Why not?

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The valve stem hole on the wheels are not dead center. The tube stem is. So it will flex and probably pull the rubber at the stem loose. You would also need a really wide flap. Guess its possible if you found tubes with an offset. Other than then that the big warning on the wheel saying not to use an inner tube. Have at it.

Or carry 2 or 3 cases of spray foam, permatex and duct tape. On a Sidewall gash tape the inside. Seal with permatex. Duct tape the outside. It will generally hold once dry. Least well enough for the ctis to keep up. If not then fill er full of foam.

 

[jwchameleoncorp]

The valve stem hole on the wheels are not dead center. The tube stem is. So it will flex and probably pull the rubber at the stem loose. You would also need a really wide flap. Guess its possible if you found tubes with an offset. Other than then that the big warning on the wheel saying not to use an inner tube. Have at it.

Or carry 2 or 3 cases of spray foam, permatex and duct tape. On a Sidewall gash tape the inside. Seal with permatex. Duct tape the outside. It will generally hold once dry. Least well enough for the ctis to keep up. If not then fill er full of foam.

Thanks for the insight! Always trying to think of alternatives. So many good ideas in this group.

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[Curtisje]

I carry a good tire plug kit. I can usually plug a hole before the tire is flat. A stubborn hole needs lots of plugs, just keep putting them in there until it stops leaking. I've even done this successfully on the sidewall of an LAV-25 tire. A plug kit will save your butt more than once. A plug kit plus either on board air or a portable air tank.

 

[jwchameleoncorp]

I carry a good tire plug kit. I can usually plug a hole before the tire is flat. A stubborn hole needs lots of plugs, just keep putting them in there until it stops leaking. I've even done this successfully on the sidewall of an LAV-25 tire. A plug kit will save your butt more than once. A plug kit plus either on board air or a portable air tank.

100% agree! I've kept them on all my vehicles for years. So handy!

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