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Spare tire size different then the (4) Four tires

sherdep

sherdep

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Not sure if any of you look at the spare but was looking under my truck to see how I am going to connect the lights I want to add under the tailgate and happen to notice the spare tire is a different size then the (4) Four main tires
Factory Tires are 285/60R20
Spare Tire is 275/70R18

Doesnt make sense to me because I was always told with a 4x4 and or on a Limited Slip Differential you never run a different size tire

Do you think I am reading too much into this?

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All SRW trucks come with a 18" spare regardless of tire size.

FWIW I run both 285/60R20 and 275/70R18 tires on my truck and they are similar enough in size that I don't have to adjust the speedo when I swap wheels/tires.
 
It is a new truck. The spare should be the same as the tires on the four corners. I would be talking to the dealer.
EDIT: @AH64ID replied at the same time. I guess, the spare is meant to be temporary. Glad my dually spare is the same as the other six; although the rims are different if you have the allow wheels.
 
MEGA HO said:
My Ltd has 20" rims and my spare is 18", I'm sure it is 18 on all trims
Click to expand...
Thanks for the reply as well
Guess I was over thinking it that it would have a factory 20 under there
 
The 18” wheel doesn’t bother me, but I was pretty upset to find that it was a HT tire vs the AT’s the truck came with. I ditched the junk transforce HT for a used like new AT pretty quick.
 
When I ordered new tires, I've ordered x5 35x12.5R20 Nitto RG, by luck I've something to to do under the truck and I've noticed my spare was 18" so I quickly called and cancelled one of the tires. They didn't have similar size for 18" wheel and I never got around ordering a proper 35" spare.
 
Yeah, I've been meaning to order a new spare to match my 35's too, but haven't. One day that will bite me in the rear as I'll inevitably have a flat on the rear and be forced to "rotate" the spare to the front tire. I need to get on that, thanks for the reminder.

Anyway, with the stock setup it's minimal. To put it into perspective, we're talking about a 0.3" difference. That's 0.15" (5/32) radius, which is the difference between a new, and half worn tire. Granted, the same size is ideal, but in a pinch (you've got a flat) it's close enough and won't hurt anything.
 
I’m moving to 37s and will be running a 35” spare. I’ll just do the shift to the front dance if I have to. It’s not going to hurt anything, though it may make the ABS unhappy. I also carry plugs and a sidewall patch kit, so the likelihood of needing to use a spare is somewhat reduced.
 
The OP says, "the spare tire is a different size then the (4) Four main tires"

The wheels are different but the tires are the same size.
You have five wheels with 33" tires.
 
Our Ram 3500 came with Firestone Transforce HT's, but we traded them in within days of the truck's purchase for some better snow traction tires. The listed diameter of the Transforce in the 285 60R20 size is the exact same 33.4 inches as our Toyo C/T's tires on our truck in its 275 70R18 size. No difference.
 
I don't think it was confusion over the P-metric sizes. They're very similar but not "the same." Semantics maybe, but also maybe the precise concern.
One is 33.5" while the other is 33.2". As the thread has already discussed, the minimal difference isn't an issue, but I think that was the concern.
Normally, I'd assume you're both correct that the confusion was based on the wheel size, but the OP posted the conversion which implies they're aware that 2 different metric sizes can be the same size tire even with different wheels. These technically aren't though. IDK, maybe I take things too literal, but I think the concern was the 0.3" difference.
 
AH64ID said:
None of the tires on these truck are P-metric, they are LT's even with their metric sizing.
Click to expand...

Correct.

P-metric is a passenger tire. Meant for passenger cars, SUV's and most 1500 pickups.

Anything carry weight will have an LT tire.
 
Confused???
P-metric is just a sizing format, no? When shopping for tires, LT is a truck tire (Light Truck, not tractor). So they'd obviously be a truck tire (LT) on these but sized in a metric format. Thus I used p-metric for discussion purposes. When shopping for tires you'd obviously want a truck tire versus passenger car, but the format is the same. My apologies if I've looked at this terminology wrong, I'm not a tire shop guy and didn't mean to cause confusion.
 
Shots said:
Confused???
P-metric is just a sizing format, no? When shopping for tires, LT is a truck tire (Light Truck, not tractor). So they'd obviously be a truck tire (LT) on these but sized in a metric format. Thus I used p-metric for discussion purposes. When shopping for tires you'd obviously want a truck tire versus passenger car, but the format is the same. My apologies if I've looked at this terminology wrong, I'm not a tire shop guy and didn't mean to cause confusion.
Click to expand...
There is no such thing as P- Metric…. There is P tires and then metric measurement's but the P has nothing to do with the metric measurements P is a ply rating
 
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