I have a 98 zj that I'm getting ready to put a 3.5" iron rock lift on. My problem is that it has the 17" Liberty wheels on it so I have no idea what size tire I can fit with the lift. What size tire will work? I want to go as big as possibly with no other modifications

 

I guess this is going to be a Mall Crawler and flex isn't an issue? If so just bump stop the hell out of it to stop most movement and see what you can stick on there.


Call Iron Rock and ask them on the size you can fit on a stock ZJ.

 

Remove enough sheet metal and you can run 40s. the wheels are whats going to limit you, theres not enough offset on stock wheels to push them far enough out do they wont rub the inner fender or control arms while turning.

 

The 17 vs 15 inch tire won't make a difference in regards to what you can fit.

Probably 31s, or whatever the metric equivalent is. Not as familiar with the ZJs.

 

You can calculate the rolling diameter of a tire by it's size and rim diameter. For instance, my 245/70R16s are 9.616" (English equivalent of 245mm) wide times 70% for height equaling 6.731". double that plus the rim size gives you 29.462" rolling height.

SO, if you want 31" overall, subtract the rim (17") becomes 14" divided by 2 is 7" or 178mm rubber height above the rim gives you a 225/75R17 or a 255/70R17.

In other words, the profile ratio determines the overall height. 70's are wider than 75's. For rubbing, width hurts you on stock rims unless you use wheel spacers. I don't like wheel spacers for safety reasons, but may be alright for mall crawling.

 

Ok I think I understand. I'm thinking 256/70/17 then. That should give me a 31" tire so it will tuck into the fender pretty well and also keep me around that 10.5 range to prevent rubbing

 

I have 32-10.50-15s on my ZJ with a 4" lift and 3.75" of back spacing on the wheels, no rubbing what so ever. A 265-75-17 is about 32", but not as wide as a traditional 32"tire.

 

So would I be better off with a 255/70/17 to be on the safe side? I don't want to have to do a whole bunch of modifications

 

Keep in mind you'll probably have to mount them yourself because most tire stores now won't mount anything but the approved tires for your jeep because of insurance liability. They'll sell them to you, you mount them, then take them back to have them balanced. That way they aren't libel for any damages to your vehicle caused by the tires. Insurance companies suck!

 

I've never heard that or had a problem with it. You could always bring them the wheels and tires and ask the shop to mount them.

 

That's the way to go if you can do it. I only had the one vehicle. The best trick was getting 4 33x12.5s into my ZJ to put on my truck!

 

Dave is correct last week we took the Lincoln Town Car in for new tires and I wanted a size larger and they would fit fine......They nixed it only what the car shipped with on the door panel.


New Washington rules to help us from ourselves

 

I've bought and had multiple sets of oversized tires mounted and installed from discount. I think it might be a store by store basis, but from my experience, if they'll fit they'll put them on. Only thing I've been told no too is mounting a really wide tire on a narrow rim(12.50 on a 7.5") or stretching tires(which there's a shop in town that will do it for you) so just mounting on an out of spec wheel.