Switching from Dunflops to an LT tire...Should I buy 4 or 5

M

Mabuse

New member
I want to get rid of the stock Dunlops and get a LT tire (I'm most interested in the Goodyear Silent Armor). I am not going to upsize, I am sticking with the 265/65/17 size of the stock tires. I would like to save money and only buy 4 tires and keep the Dunlop spare.

However, the user manual warns that, due to the sensitivity of the 4WD system, all tires should be the same size, manufacturer, and weight. Isn't a light truck tire a lot heavyer than the stock Dunlop? If I get a flat and put on the Dunlop spare, could I harm the 4WD, or cause it to be less effective?
 
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Mabuse said:
I want to get rid of the stock Dunlops and get a LT tire (I'm most interested in the Goodyear Silent Armor). I am not going to upsize, I am sticking with the 265/65/17 size of the stock tires. I would like to save money and only buy 4 tires and keep the Dunlop spare.

However, the user manual warns that, due to the sensitivity of the 4WD system, all tires should be the same size, manufacturer, and weight. Isn't a light truck tire a lot heavyer than the stock Dunlop? If I get a flat and put on the Dunlop spare, could I harm the 4WD, or cause it to be less effective?
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:confused: In the 265/65/17 the only GYSA is a P tire. In the 70 there's a P and a LT. Either way, if you don't upsize the main tires the Dunlop spare should be fine. The spare's dimension can be off many ways except O.D. It's all about the outside diameter... If it is equal or very close it'll work fine as a spare with no damage to anything.

:cheers:
 
Re: Re: Switching from Dunflops to an LT tire...Should I buy 4 or 5

CJ3Flyr said:
:confused: In the 265/65/17 the only GYSA is a P tire. In the 70 there's a P and a LT. Either way, if you don't upsize the main tires the Dunlop spare should be fine. The spare's dimension can be off many ways except O.D. It's all about the outside diameter... If it is equal or very close it'll work fine as a spare with no damage to anything.

:cheers:
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x2
 
What's the largest you can stray when comparing the 4 main tires to the spare if you ever had to throw a smaller spare on? Assuming it's a 4WD, and cannot be put into 2WD to compensate. I see no issues in using a 265/65/17 spare for a set of 265/70/17 tires, but what about using a 265/70/17 spare for a set of 285/70/17's? Could you air down the other 3 tires to make them even enough to not aggravate any sensors or damage anything?
 
HB 4X4 said:
What's the largest you can stray when comparing the 4 main tires to the spare if you ever had to throw a smaller spare on? Assuming it's a 4WD, and cannot be put into 2WD to compensate. I see no issues in using a 265/65/17 spare for a set of 265/70/17 tires, but what about using a 265/70/17 spare for a set of 285/70/17's? Could you air down the other 3 tires to make them even enough to not aggravate any sensors or damage anything?
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I don't know... I do know the following:
1) There is some amount of tolerance. A flat tire with stock tires doesn't = VSC/TRAC lights on. And that's far more than an inch. One of the concepts of having VSC is to maintain control in an event like a blowout.
2) A long, high speed drive with different diameter tire will cause the differential to heat up. If you have some fresh, good gear oil there should be no damage in a 55mph or slower 50 mile drive. Obviously, the closer the tire diameter the better. The big scary stuff about tire diameter is related to older limited slip technologies such as Posi or Sure-grip that has clutch packs or cones. We basically have open differentials as far as this goes.

Trying to read your mind... I would look for a cheap or slightly used 255/75/17. Fill it to max sidewall psi and hang it underneath. It's about the biggest diameter that'll fit, it's light, it tucks the spare up higher and at max sidewall pressure it will compress very little preserving the full diameter when installed.

As far as deflating the remaining three tires goes: I'd consider it if my speeds were going to be low. I'd be afraid of overheating and blowing one of my tires.

:cheers:
 
CJ3Flyr said:


I don't know... I do know the following:
1) There is some amount of tolerance. A flat tire with stock tires doesn't = VSC/TRAC lights on. And that's far more than an inch. One of the concepts of having VSC is to maintain control in an event like a blowout.
2) A long, high speed drive with different diameter tire will cause the differential to heat up. If you have some fresh, good gear oil there should be no damage in a 55mph or slower 50 mile drive. Obviously, the closer the tire diameter the better. The big scary stuff about tire diameter is related to older limited slip technologies such as Posi or Sure-grip that has clutch packs or cones. We basically have open differentials as far as this goes.

Trying to read your mind... I would look for a cheap or slightly used 255/75/17. Fill it to max sidewall psi and hang it underneath. It's about the biggest diameter that'll fit, it's light, it tucks the spare up higher and at max sidewall pressure it will compress very little preserving the full diameter when installed.

As far as deflating the remaining three tires goes: I'd consider it if my speeds were going to be low. I'd be afraid of overheating and blowing one of my tires.

:cheers:
Click to expand...

Thanks Chris. I am just trying to find other solutions to getting larger tires than throwing a spare on the roof, or getting an ugly tire carrier in the back.
 
HB 4X4 said:
Thanks Chris. I am just trying to find other solutions to getting larger tires than throwing a spare on the roof, or getting an ugly tire carrier in the back.
Click to expand...

I hear ya...:D I don't know how far out you wheel but I think you'd do fine with a 255/75/17 unless you were hundreds of miles out in the middle of Baja and are in a high speed race:biggrin2:

One of those cheap tirerack Jeep BFG's might be a good choice.

:cheers:
 
CJ3Flyr said:
I hear ya...:D I don't know how far out you wheel but I think you'd do fine with a 255/75/17 unless you were hundreds of miles out in the middle of Baja and are in a high speed race:biggrin2:

One of those cheap tirerack Jeep BFG's might be a good choice.

:cheers:
Click to expand...

Even with the full-time 4WD the 255 is large enough to not do any harm?
 
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