Open Differentials and small spare

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I heard Range Rovers have open differentials so if you have oversized tires 35” and have to use your spare 31” having one off sized tire is okay in emergency as long as you don’t lock up your differentials during use with spare. Would this also be true for the 80 series as well? Thanks.
 
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The concern is not in the front or rear diffs but in the center diff (transfer case) with the viscous coupler. If you have already removed it then it won't be an issue but driving too long and/or fast would likely burn up the VC and they are NLA from toyota as far as i know. Many people remove them. they were not part of the 100 series design which uses the same transfer case sans VC.
 

ppc

M Go Blue
 
 
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All the passenger cars that I have seen that use a compact spare caution the operator not to exceed a vehicle speed above 50 MPH and not travel more than 50 miles give or take small speed and mileage differences. There are three components to those warnings. First would be safety that the vehicle handles differently, second would be tire construction limiting load capacity and heat buildup. Third is the differentials in constant action because each wheel operates at a different RPM which can cause heat buildup and wear on spider gears and other internals. In my opinion both would apply to AWD/4WD vehicles and specifically adding a center diff with optional viscous coupler makes our vehicles possibly more susceptible to those three components.
 
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I have 35” tires now so sounds like I should just carry my full-size 35” spare on my roof. Wanted to carry a oem sized spare in the factory location for emergencies. Definitely be walking the LC under 50mph probably far less.
 
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I have 35” tires now so sounds like I should just carry my full-size 35” spare on my roof. Wanted to carry a oem sized spare in the factory location for emergencies.
I could be wrong, but i seen to remember reading a thread were a 35 will fit under the truck in the factory location with a few easy modifications. Do a search, i think you'll find the thread I'm thinking of.
 
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If you are going really slow and for a short distance different tire sizes won't be a major issue. Longer distance and higher speeds can cause havoc with the differential.

Ideally the spare will be the same as the other tires so you can slap it on and drive as usual.
 
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I could be wrong, but i seen to remember reading a thread were a 35 will fit under the truck in the factory location with a few easy modifications. Do a search, i think you'll find the thread I'm thinking of.
I fit a worn 315/75/16 in the stock location, however I had to remove the factory installed hitch. I also raised the spare carrier 2 inches. It still hangs pretty low but it's servicable for easy/medium wheeling. For more advanced stuff you can strap it down in the cargo area.
 
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I fit a worn 315/75/16 in the stock location, however I had to remove the factory installed hitch. I also raised the spare carrier 2 inches. It still hangs pretty low but it's servicable for easy/medium wheeling. For more advanced stuff you can strap it down in the cargo area.
Yep. That’s what I have too and try is brand new though. Definitely be crawling annoyingly slow back home with the smaller 31” spare
 
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Why is that?
In most cases it's a bad idea. A spare is heavy and difficult to get up and down from the roof. Its also heavy for its size which raises the center of gravity when mounted up top. In addition its constantly exposed to the sun/UV so it will degrade faster over time than a tire stored underneath.

Can't think of any pros to storing one up top like that.
 

LC4LIFE

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It's the spider gears at risk when driving with drastically different diameter tires. I would do it very cautiously and only for a short distance, if I had too.
 
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You can find my detailed story elsewhere, but a 2" diameter difference in a spare at 100 MPH for 15 miles will overheat the pinion in a Chrysler 9 inch rear diff to the point of shearing the pinion and starting the rear axle on fire.

Low and slow, baby!
 
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In most cases it's a bad idea. A spare is heavy and difficult to get up and down from the roof. Its also heavy for its size which raises the center of gravity when mounted up top. In addition its constantly exposed to the sun/UV so it will degrade faster over time than a tire stored underneath.

Can't think of any pros to storing one up top like that.
I got a Uv storage bag that I use for my tires I store outside of my house. Each tire is wrapped around a so-called Uv protective material. Would use that if I did throw a tire on the roof.

Now what about everyone that carry a roof top tent? They weigh far more then a spare tire. Full 5 gallon gas tanks and a sorts of heavy stuff people carry on their roof racks?

I carry nothing at this point and reason for asking. I prefer not to either. However. I don’t want to waste valuable real estate inside the cabin to carry a 35” spare. I also don’t want to have a heavy steel rear bumper just to carry a spare. Not in it for the looks so either below or roof.

I do like those rear body mounted swing arms I see on the JDM 80 series from Japan. I would drill some holes in the body of the 80 to accommodate a swing arm. Just don’t want those heavy steel rear bumpers. SMH what to do.
 
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Just don’t want those heavy steel rear bumpers. SMH what to do.
You really don't need to buy a heavy steel aftermarket bumper to get a swing away tire carrier. You could build your own swing away tire carrier, below are 2 photos of the one i built. It's not an expensive, nor a difficult project to complete.

1574331423927.png


1574334727434.png
 
Last edited:

jonheld

 
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Why is that?
Because every time I see it, I feel like these people have never taken a basic physics course. Same Idea with the knuckleheads that have highlift jack mounted on the hood.

You have to think about what would happen during a collision.

A 315/75R16 tire WITHOUT a rim is 65-75 lbs. Add a rim and you're pretty close to 100 lbs.
Now let's use a strap that you bought at Home Depot to "strap it down". If that doesn't hold, then how are you securing that fancy roof basket. With those 2 clamps on the rain gutter? Or to the factory rack? Yea, that's gonna end well.

Folks that carry roof mounted tents have spent the money on proper, full length roof racks that are secured with 4 clamps per side, and the roof top tent is securely mounted to the rack in multiple places.

My point is that there are proper ways to carry loads.
 
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Because every time I see it, I feel like these people have never taken a basic physics course. Same Idea with the knuckleheads that have highlift jack mounted on the hood.

You have to think about what would happen during a collision.

A 315/75R16 tire WITHOUT a rim is 65-75 lbs. Add a rim and you're pretty close to 100 lbs.
Now let's use a strap that you bought at Home Depot to "strap it down". If that doesn't hold, then how are you securing that fancy roof basket. With those 2 clamps on the rain gutter? Or to the factory rack? Yea, that's gonna end well.

Folks that carry roof mounted tents have spent the money on proper, full length roof racks that are secured with 4 clamps per side, and the roof top tent is securely mounted to the rack in multiple places.

My point is that there are proper ways to carry loads.
I agree. I actually have never carried anything on my roof or hood on any of my vehicles.

Although I would say a spare tire would cause far less lift then a roof top tent. Most rain gutter cross bars hold about 130lbs each. The rain gutter itself also have limits of how much weight it can safely hold as well before they buckle. Either way. I don’t like either.

I’m really thinking about putting smaller tires on so I can carry a full size matching spare in the original intended location and not thinking about it.
 
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You really don't need to buy a heavy steel aftermarket bumper to get a swing away tire carrier. You could build your own swing away tire carrier, below are 2 photos of the one i built. It's not an expensive, nor a difficult project to complete.

View attachment 2138564
View attachment 2138573
That’s some nice work. After considering it. I just don’t want to take the time to swing my tire out of the way each time I want to access the rear cargo area. Might have to go back to smaller tires and stock height so my LC doesn’t look goofy.
 
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In most cases it's a bad idea. A spare is heavy and difficult to get up and down from the roof. Its also heavy for its size which raises the center of gravity when mounted up top. In addition its constantly exposed to the sun/UV so it will degrade faster over time than a tire stored underneath.

Can't think of any pros to storing one up top like that.
I ran all the time with one on the roof on my 60 series. When I'd go out into the Oregon outback, I carried two full size spares (33x12.5). Flats were not uncommon. Extra tire and gas on the roof in my Confer rack. No issues, not problem getting it down. I didn't leave it on the roof all the time, only when heading out into the boonies, but this was for better mileage. However, if UV bothers you, just put a cover on it.
 
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I just don’t want to take the time to swing my tire out of the way each time I want to access the rear cargo area.
I do have to admit, some times when i go to the grocery store, and some jack wad parks way to close to me.

I think to myself it would be a lot easier to load my grocery's, if i didn't have to deal with that tire carrier.

But at the same time, i sure do like the extra ground clearance i get while driving off road.

So with most things in life, the swing out tire carrier is a trade off.
 
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