this is on the wifes 99 grand cherokee limited. I went to the local tire shop as well as spoke to a shop I found online and both said the same answer. Right now theres 245/75/16 I asked for the same diameter but a little wider so I was told 265/60/18 will fit(18 as thats the size of the new rims). So I bought them of ebay and now there here, theres no way they'll fit. I looked and a 2" lift will be able to clear 30" tires, but will the width fit without rubbing. I don't want to mount 1 as now its used. I looked and the recomended 2 up size is 255/55/18. What to do? Lift ot buy new tires...again?

 

Lift it. You could most like get by with coil spacers in the front to clear those tires. The 245/75 16 on there now is taller than the 265/60 18. How much offset do the wheels have?

 

No both tires are about 30.5 in diameter but the latter is about 1.5 inches wider. I'm not sure of the offset, what ever stock is. Thats the part thats confusing, I also did a tire conversion on the net and I got the same answers as I did from the tire guys. I put the new tires next to the old ones and theres abot 2 inches difference. I took a tape measure and the 245/75 are about 28.5 inches in diameter so what gives?

Stock Tire - 245/75R16 >Search Tires Tire 1 - 265/60R18 >Search Tires
Section Width: 9.64 in 245 mm
Section Width: 10.43 in 265 mm

Rim Diameter: 16 in 406.4 mm
Rim Diameter: 18 in 457.2 mm

Rim Width Range: 6.5 - 7.5 in
Rim Width Range: 7.5 - 9.5 in

Overall Diameter: 30.46 in 773.68 mm
Overall Diameter: 30.51 in 774.95 mm

Sidewall Height: 7.23 in 183.64 mm
Sidewall Height: 6.25 in 158.75 mm

Radius: 15.23 in 386.84 mm
Radius: 15.25 in 387.35 mm

Circumference: 95.69 in 2430.5 mm
Circumference: 95.84 in 2434.3 mm

Revs per Mile: 682.8
Revs per Mile: 681.7

Actual Speed: 60 mph 100 km/h
Speedometer1: 59.9 mph 99.8 km/h

Speedometer Difference: - Speedometer Difference: 0.161% too slow
Diameter Difference: - Diameter Difference: 0.17%

 

If there's 1.5 inches difference between the two (and you're sure!) and your new rims have the stock backspacing, you can look at your stock tires in the back and see if they if you have more than .75 between the sidewall and the inside (leaf spring, frame, whatever the widest part is). If you do, they will fit that way.

Do the same on the wheel well (the new tires will stick out .75 farther than the old).

 

Well I took the stocker off and put just the rim on and the offset is different.
I looked at the ad and it says that the offset is +40mm. But the rims are made for this jeep, now it looks like I might have a clearance problem turning the wheel. I put the 2 wheels side by side and they look the same diameter, I guess that the weight makes quite a difference.