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Discussion Starter #1
Ok, so the stock size on a Bridgestone Dueler sidewall reads 255/70/R18

I'm looking at either 295/65/R18 or 275/70/R18

The 275 looks like it would be the closest to my stock size that they make and the 295 seems like it would be a little taller, but with slightly narrower rubber.

Which one sounds like the better fit for a completely stock Jeep? I'm thinking of adding a BB, but the cash just isn't there right now. I don't do a whole lotta wheelin and this is a DD Jeep that primarily sees highway miles.

What say you Jeep shoe gurus?
 

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Discussion Starter #2
I'm gonna end up going blind shopping for fucking tires.

So, after another look at a few tire sizing charts, it looks like the first number relates to the width of the tire and the second is the one that denotes height as a ratio/-percentage of the first number.

That means that these two tires are almost exactly the same height (33.1 vs 33.2 in rolling diameter) but the 295 would be slightly wider, which would probably lend itself to rubbing more often during turns and while flexing.

Sound about right to anyone else?
 

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Hey Dan,

on a 275/70R18

the 18 is the rim size in inches 18"

the 275 is the width of the tire in MM

the 70 is the hight of the side wall in % to the width, 70% of 275 MM

remember there are two side wall so to find the tires hight you multiply this number by 2 and add the rim diameter.

1" = 25.4 MM

275 MM = 10.8" 70% of 10.8 is 7.56"

18" + (7.56 x 2) = 33.12"

so a 275/70R17 is the sane as a 33.12" x 10.8" 18" tire
So pretty much a 33X10.5
 

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Discussion Starter #5 (Edited)
Anyone happen to know how wide a tire you can put on the stock rim without risking a blowout? If the tire is 10.5" and I think my rims are 8.5 - is that 2.00" gonna screw me?:bawling:

No wonder people stress about this shit


EDIT: This makes me feel a little better -

Stock Tire:
255/70R18
Versus:
275/70R18
Section Width: 10.03 in 255 mm
Section Width: 10.82 in 275 mm

Rim Diameter: 18 in 457.2 mm
Rim Diameter: 18 in 457.2 mm

Rim Width Range: 6.5 - 8.5 in
Rim Width Range: Unrecognized tire size.

Overall Diameter: 32.05 in 814.07 mm
Overall Diameter: 33.15 in 842.01 mm

Sidewall Height: 7.02 in 178.30 mm
Sidewall Height: 7.57 in 192.27 mm

Radius: 16.02 in 406.90 mm
Radius: 16.57 in 420.87 mm

Circumference: 100.6 in 2555.2 mm
Circumference: 104.1 in 2644.1 mm

Revs per Mile: 648.9
Revs per Mile: 627.4

Actual Speed: 60 mph 100 km/h
Speedometer1: 58.0 mph 96.6 km/h

Speedometer Difference: - Speedometer Difference: 3.426% too slow
Diameter Difference: - Diameter Difference: 3.32%
 

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Anyone happen to know how wide a tire you can put on the stock rim without risking a blowout? If the tire is 10.5" and I think my rims are 8.5 - is that 2.00" gonna screw me?:bawling:

No wonder people stress about this shit
Lets stress a little more :D

The Stock JK Sahara Rims are 18X7.5" and have a large offset of 6.25". That doesn't leave much room on the inboard side which causes trouble with wider tires if no spacers are used with the stock rims.
Here the spacing between stock Sahara tires and rear upper CA and rear Swaybar while level.





So with a spacing of about 25mm (1") with a stock 255/70R18 you should be able to go to a 275 wide tire without rubbing on the rear upper CA's but different tire type may bulge differently and Jeep manufacturing tolerances may make it rub anyways.

The tire manufacturer gives you a from their perspective safe rim width range for each tire size. You might be able to go outside of their safe range without problems but at your own risk.
 

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Here's another variable.. Just because the tire calculations or the manufacturers spec say a tire is (should be) a certain size is not neccessarily so. Every manufacturer has a different way of measuring. For instance, my 35" 315/75R-16 (35x12.50x16) ProComp Xtreme M/Ts measured in at just over 33", factory specs say 34.6", whereas my GY Duratracs in the same size measure just over 34" and factory spec also say 34.6". A Pitbull Rocker in that size actually measures 35.2". A 2 inch difference in the same size tire is a big variable to have to deal with..
 

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Pulled the trigger on the 275/70R18 tonight.

We'll see what happens tomorrow.

If you see a set of nearly brand new Duratracs in the for sale section, you'll know why.:thefinger:
Believe me you'll like the Duratracs, I have yet to be dissapointed by them.
 

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Discussion Starter #11
Thanks. I about crapped myself when I realized I might have muffed it on the rim width, but the 275/70R18 can be safely installed on rims between 7.0 - 8.5" wide.

Now as far as space underneath goes, I might end up doing spacers if I get too much rubbing going on when I corner or when I flex a little, but that was pretty much expected.


Tire guy tells me my new Duratracs should be arriving sometime around noon today:bounce:
 

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Pulled the trigger on the 275/70R18 tonight.

We'll see what happens tomorrow.

If you see a set of nearly brand new Duratracs in the for sale section, you'll know why.:thefinger:
Dan, I'm running 295 75's and not having any issues, so you shouldn't have any issues!
 

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Discussion Starter #16
these are 275/70 18 I love them.
Heh, that looks incredibly familiar.

Got mine installed tonight and immediately hopped on the highway for about a half hour drive home. Rides pretty well. Not sure about road noise yet since I was rockin & rollin down the turnpike. So far, me likey. :cookiemonster:

The rubbing's pretty annoying in a full turn, so I may end up with some spidertrax spacers and a mild lift to make them look a little more normal in the wheel wells, but for now, I'm digging them.

I'll have to remember to snap a few pics for my scrapbook tomorrow.
 

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ARe they rubbing on the plastic airdam.?
 

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Christ, I think I can see my house in those pictures...
 
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