Tires 33's on 18" wheels
05-16-2009, 05:59 AM
#11
JK Enthusiast
Join Date: Sep 2007
Location: North, TX
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Im still waiting on my Backordered tires but I am going with BFG 33" MT KM2 on my 18" with 1.5" spacer and a 2" spacer lift and yes its not cheap. The lift may not be needed but going with it just to give it a bit more room.
When I wear down these tires I will be ready to try a different wheel and tire combo and maybe a real suspension lift may even go up to 35" maybe.
When I wear down these tires I will be ready to try a different wheel and tire combo and maybe a real suspension lift may even go up to 35" maybe.
05-16-2009, 10:50 AM
#12
JK Super Freak
Join Date: Sep 2007
Location: Oxnard, CA
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Installed Goodyear MT/R 275/70 R18 with Kevlar last week with no lift needed on my 2009 JK Sahara. These tires are 33.6 diameter, and they add 4.5 inches in circumference over what the 255/70 R18 Bridgestone Dueler ATs measured.
4.5 inches does not seem to be much, but you can feel the effect of the gear ratio change. One very positive note about the tire upgrade is the JK feels much more stable on the road.
4.5 inches does not seem to be much, but you can feel the effect of the gear ratio change. One very positive note about the tire upgrade is the JK feels much more stable on the road.
Are you sure?? The dueler should have been real close to 32" diameter. Something doesn't sound right. 2.25" would be what your Jeep was raised with the tires fully inflated, not a bad thing at all, but I somehow find the difference unbelievable.BTW, how quiet are those tires?
Last edited by CIJeep; 05-16-2009 at 10:54 AM.
05-17-2009, 10:57 AM
#13
JK Newbie
Join Date: Apr 2009
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Are you sure?? The dueler should have been real close to 32" diameter. Something doesn't sound right. 2.25" would be what your Jeep was raised with the tires fully inflated, not a bad thing at all, but I somehow find the difference unbelievable.BTW, how quiet are those tires?
The OEM Dueler spec was 32.1" dia. and the MT/R was 33.4" dia., on paper. But the actual circumference was 101.25" (which is 32.23" dia) for the Dueler and 105.75"(which is 33.66"dia) for the MT/Rs. The math shows, using the actual circumference, both tire diameters were more than the spec. The result was a raise of about .72", not 2.25" because the 4.5 inches in the original post refers to circumference, not diameter. Sorry if that was not clear.
Re "something doesn't sound right," you bet! Don't trust the factory spec. Get the tape measure out a check the tires inflated to 35psi, then you will know exactly how the taller tire will effect the gear ratio.
Bottom line, by adding the 4.5 inches in circumference the MT/Rs changed the gear ratio from 3.73:1 to just under 3.57:1. With the auto trans, which has a final drive ratio of .69 the change dropped the O/D from 2.57 to 2.46. What all that means is that there is more down shifting by the trans since the 202HP does not have the umph
to handle the ratio change.