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-   -   URGENT! tire size question- wife stranded (http://www.jeepgarage.org/f181/urgent-tire-size-question-wife-stranded-72053.html)

SteelBlueWK 02-23-2014 05:33 PM

URGENT! tire size question- wife stranded
 
Wife has my jeep. Hit pothole- blew out right rear tire. Rodian HP 20" on srt8 rims. Can I run the factory spare even though it's 1/4" shorter in overall diameter?

Rodian is 29.75" dia

Factory Fortera is 29.5" dia

I don't want to ruin the rear diff but seems this is small difference in tire size might be OK?

Scottina06 02-23-2014 05:40 PM

Yes...but just for a short time imho

SteelBlueWK 02-23-2014 05:42 PM

Re: URGENT! tire size question- wife stranded
 
Quote:

Originally Posted by Scottina06 (Post 980870)
Yes...but just for a short time imho

Scott, thank you so much for getting back quickly. So you feel even that small size difference could damage the diff? She's 1 1/2hrs away right now. So you wouldn't recommend driving that long. We have AAA and can have it towed if need be.

Scottina06 02-23-2014 06:49 PM

How many miles? I would just have it towed if your worried or can't get a tore local. I think it would be ok....but can't say 100%

SteelBlueWK 02-23-2014 07:02 PM

Re: URGENT! tire size question- wife stranded
 
Jeep is on a roll-back heading home now. It's 95 miles away and I didn't want to risk damaging the rear diff with two different sized tires.

Now I have to find a new tire and have the rim checked to make sure it's OK. Wife told me it has some 'scratches' around the lip because she couldn't get off the road right away and had to slowly roll with it for about a mile. Won't know how bad it is till I see it later tonight.

Strongjeff 02-23-2014 10:17 PM

Re: URGENT! tire size question- wife stranded
 
Quote:

Originally Posted by SteelBlueWK (Post 980865)
Wife has my jeep. Hit pothole- blew out right rear tire. Rodian HP 20" on srt8 rims. Can I run the factory spare even though it's 1/4" shorter in overall diameter?

Rodian is 29.75" dia

Factory Fortera is 29.5" dia

I don't want to ruin the rear diff but seems this is small difference in tire size might be OK?

you should be fine for temporary use, I don't think it will hurt any thing :thumbsup:

SteelBlueWK 02-24-2014 12:45 PM

Re: URGENT! tire size question- wife stranded
 
UPDATE: The roll-back flatbed arrived at my house around 9pm last night. Thank you AAA! This one tow paid for the membership- glad I got it now.

The tire was completely destroyed. Both side walls disintegrated and separated from the tread, but it stayed on the wheel. Looking at the tire damage I was expecting the wheel to be toast but it's not. There is one small 1/2" scrape on the outside lip and that's it. You can't even notice it when you step back a couple of feet. No wheel-well damage either.
I ordered another tire locally. It should be in tomorrow, then I can get it mounted & balance and get my Jeep back on the road.

2005JGC 02-24-2014 10:37 PM

Re: URGENT! tire size question- wife stranded
 
I would have agreed with Scott on this one, 1/4 inch isn't a lot but a 1600 dollar transfercase is ;) especially in your case when you have AAA and a free ride home.

Strongjeff 02-24-2014 10:38 PM

Quote:

Originally Posted by 2005JGC (Post 981744)
I would have agreed with Scott on this one, 1/4 inch isn't a lot but a 1600 dollar transfercase is ;) especially in your case when you have AAA and a free ride home.

Not transfer case. If it was on the front then I could see it being an issue. More like undue stress on diff.

2005JGC 02-26-2014 01:14 AM

Re: URGENT! tire size question- wife stranded
 
When you reduce the size of A wheel then you effectively change the output ratio for that axle. So now your rear axle is spinning faster than your front axle... burning up the transfercase.

Yes, your diff clutches wont appreciate a long trip slipping against each other either.

Strongjeff 02-26-2014 01:20 AM

Quote:

Originally Posted by 2005JGC (Post 982508)
When you reduce the size of A wheel then you effectively change the output ratio for that axle. So now your rear axle is spinning faster than your front axle... burning up the transfercase.

Yes, your diff clutches wont appreciate a long trip slipping against each other either.

Well if thats the case then whats the point behind a donut spare on a 4x4. I have seen them on 4x4's...

SteelBlueWK 02-26-2014 12:57 PM

Re: URGENT! tire size question- wife stranded
 
My Jeep is back on the road! Purchased a new tire yesterday. The wheel checked out OK, not bent or cracked. Put new tire/wheel on last night and drove it to work today.

I did find some additional minor damage from the tire tread rubbing inside the wheel well. It caught the plastic rivit that holds the lower rocker panel inside the wheel well and ripped it off. I replaced that easily. Also, the separated tread rubbed through the rear sway bar end link rubber boot, exposing the grease pocket. I'll replace that this weekend.

Re- donut spares: I would think that the overall diameter of any donut spare should match the other tires on any vehicle. Otherwise different sized tires could interfere with TC, ABS or other stability systems.


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