Optimaldave Posted March 13, 2012 Share Posted March 13, 2012 Logic tells me I can mismatch tire sizes front to rear as I have a RWD and many muscle cars have done it but can someone confirm that is true for the comanche for me? I have a ton of mostly worn tires but I can make a set of good tires for the Jeep with a pair of 245's up front and 30.5's rear. This shouldn't cause any harm should it? Also seems the PO put some 2" BB spacers up front but I don't believe any rear lift so the added rear height may actually level it (if it is actually off, I can't tell if the shackles are stock or not as of yet) Sorry for a kind of ignorant first post :P Thanks Dave Link to comment Share on other sites More sharing options...
Geonovast Posted March 13, 2012 Share Posted March 13, 2012 As long as you're 2wd, there's no issue having different size tires in the back. You may have issues with loss of power depending on your axle gearing, and your speedometer will need the gear changed to keep it accurate. Link to comment Share on other sites More sharing options...
mvusse Posted March 13, 2012 Share Posted March 13, 2012 May also need to aim your headlights a bit higher. Link to comment Share on other sites More sharing options...
Optimaldave Posted March 14, 2012 Author Share Posted March 14, 2012 As long as you're 2wd, there's no issue having different size tires in the back. You may have issues with loss of power depending on your axle gearing, and your speedometer will need the gear changed to keep it accurate. Well I'm actually going down from 31's so no power loss :D Speedo is also broken and I'm using my iPhone GPS and a speedo app so no worries there right now... May also need to aim your headlights a bit higher. haha, hadn't thought about that. Thanks 30.5" BFG MT's 245 Hankook A/T's Definately has no lift on the rear but 2" on the front so some lift shackles shall be in her future Thank you guys Link to comment Share on other sites More sharing options...
Eagle Posted March 14, 2012 Share Posted March 14, 2012 Logic tells me I can mismatch tire sizes front to rear as I have a RWD and many muscle cars have done it but can someone confirm that is true for the comanche for me? I have a ton of mostly worn tires but I can make a set of good tires for the Jeep with a pair of 245's up front and 30.5's rear. This shouldn't cause any harm should it? 245 by what? And when you say 30.5s ... that's not a tire size. Are you really talking about 31x10.50s, which are typically 30.5" in diameter, or are you talking about 30x9.50s, which are typically 29.5" in diameter? 245/75-15s are also 29.5" in diameter. 245/70-15s are 28.5" in diameter. 245/75-16s are 30.5" in diameter. What do you have? Link to comment Share on other sites More sharing options...
Optimaldave Posted March 14, 2012 Author Share Posted March 14, 2012 Logic tells me I can mismatch tire sizes front to rear as I have a RWD and many muscle cars have done it but can someone confirm that is true for the comanche for me? I have a ton of mostly worn tires but I can make a set of good tires for the Jeep with a pair of 245's up front and 30.5's rear. This shouldn't cause any harm should it? 245 by what? And when you say 30.5s ... that's not a tire size. Are you really talking about 31x10.50s, which are typically 30.5" in diameter, or are you talking about 30x9.50s, which are typically 29.5" in diameter? 245/75-15s are also 29.5" in diameter. 245/70-15s are 28.5" in diameter. 245/75-16s are 30.5" in diameter. What do you have? I stand corrected, I don't know where 30.5 came from. The rears are a 30x9.5 R15 and the fronts are 245/75 R15 So off your statement I'd say I'm splitting hairs in sizes anyways Cheers Link to comment Share on other sites More sharing options...
Eagle Posted March 14, 2012 Share Posted March 14, 2012 So off your statement I'd say I'm splitting hairs in sizes anyways Pretty much. Let's see if this will show up large enough to read: Link to comment Share on other sites More sharing options...
Abyx Posted March 15, 2012 Share Posted March 15, 2012 You want little tires in front and big in the back??? 31x10.5r15 in the back and 215/70/r15s in the front. About a 3" difference in tire sizes. :wrench: Link to comment Share on other sites More sharing options...
mvusse Posted March 15, 2012 Share Posted March 15, 2012 4.5" lift, 33x12.50R15 on back, P235/75R15 on front. (Front tires got replaced with 33" tires right after I took this picture.) Link to comment Share on other sites More sharing options...
mnkyboy Posted March 15, 2012 Share Posted March 15, 2012 38.5 x11 front and and 33x12.50 rear. Link to comment Share on other sites More sharing options...
Optimaldave Posted March 17, 2012 Author Share Posted March 17, 2012 So off your statement I'd say I'm splitting hairs in sizes anyways Pretty much. Let's see if this will show up large enough to read: Thanks all for the help And thanks Eagle for the chart, that is an awesome one for sure. Cheers Dave Link to comment Share on other sites More sharing options...
Eagle Posted March 17, 2012 Share Posted March 17, 2012 In that chart, you will see that there are two columns marked "Revolutions per mile." The one under "Theoretical" is filled in for every tire. Those values are calculated based on the tire dimensions. The other one, under "Actual," doesn't have a value for every tire. Where the "Actual" numbers are filled in, they were taken directly off manufacturers published tire specs and should be considered more accurate than the column under "Theoretical." The "Theoretical" revolutions per mile numbers don't account for sidewall squat, which (as you can see looking at the tires that show a manufacturer's static radius) reduces the rolling radius to less than half of the calculated tire diameter. Smaller radius ==> more revolutions per mile. Link to comment Share on other sites More sharing options...
carnuck Posted March 17, 2012 Share Posted March 17, 2012 I don't see 255/85R/16 on there? Link to comment Share on other sites More sharing options...
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