A question about rim size...

An 88 with 16's?????? Stock it came with 15's. You can use any 15" wrangler rim and a cheap tire as close to the same size as you can get for a spare unless you have lockers all around.

I 'sure' wouldn't put a tire that large out back. It will rip the back door off on the first off road trip. I run 33x9.5's on stock chrome Laredo 15x7" rims with a 31 as a spare.

The '75 aspect ratio usually fits on a 7" or 8" wide rim. The original tires were on a 7" rim with some trim packages coming with an 8" rim.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

An 8-10" rim should work. Couldn't you just remove a wheel and measure the rim width? it's possible to do without removing the tire, if you want the spare to match.

Most rims have the size stamped into the back side.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Thank you for the replies so far....I`m going to get one of those 48" Farmers Jack`s At this point I just want a spare tire... as long it is the same height as the other 3 tires I don`t care if it is skinnier. I`m only going to drive 10 miles or so until I get the original 35" tire fixed. I`m looking for a $50 steel rim and a $100 tire. I`m probably not the sharpest crayon in the box when it comes to tires+rim sizes..... could someone suggest a rim and a tire....please. Thanks Boris

Those 'farmers jacks' are more properly called 'widow makers' and have no business anywhere near a Jeep in my opinion!

I carry a hand cable winch called a come-a-long,

And I have a small floor jack that tucks tight behind the passenger seat for changing tires. I only need to jack it 2" to change a tire. I use the axles.....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

How is a come-a-long gonna help me change a tire?....your second idea "small floor jack" I will look into. Thanks Boris

Some folks think they can use the farm jack as a winch..... Or the come-a-long can be used to winch the Jeep up to a tree to change a tire...

Mike

Boris wrote:

If I get a 225/75/16 or 205/75/16 will this be the same height as my

315/75/16? and what rim width will I need for this tire as a spare? or am I way off base. Thanks Boris

The larger tire is about 34.6 inches tall while the smaller is 29.3 inches tall.

The smaller tire (stock size) came with a 7 inch rim although you could safely use down to a 6 inch rim.

If you just need something to get you by (emergency use only) you can probably get a used 33" (275-285mm) tire on an used 8 inch rim pretty cheaply.

Your 315/75/16 tire calculates out to be 34.6" diameter, which will vary slightly based on rim width and manufacturing variance. The 2 tires you suggested as spares will be significantly smaller diameter.

To calculate the tire height of metric sized tires, use this formula:

(width*aspect ratio*.000787) + rim diameter = height in inches

This will give you the tire diameter in inches. You're going to need a tire close to the same width, or a higher aspect ratio to end up with a tire close to the diameter you are looking for. One other option would be a larger diameter rim, but that will cost big money for rim and also tire.

if you can find a tire with 80 aspect ratio, 295 and 305 width would be close, and if you can find 85 aspect ratio, 285 width would be close. I think these are going to be pretty odd sizes to find, but maybe I'm wrong.

Chris

Not even in the ball park.

I would go with the cheaper stock 15"x7" rim that is easy to find a used tire for. 16" tires for a YJ are rare and pricey.

To start off, do you have a locker or limited slip in either axle? The answer to that will make a radical difference in what you can run.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Billy Thank you for your response, now I have some options. Boris

Mike I don`t think I have locker or limited slip, the guy I bought it from didn`t mention. After it stops raining I`ll crawl underneath and take some pictures...I just purchased the YJ......has rebuilt (Jasper or rebuilt by Jasper) 6cyl, auto transmission (new seals+new torque converter) a Rubicon

5" lift and them big tires...he also claims new brakes last year, but the rear left drum locks up at crawl speed if I brake too hard...the emergency brake doesn`t work (maybe that`s the reason the rear drum locks once in a while) needs the cables which are in the mail, and a muffler and tail pipe...also in the mail. I live in N.J. and the YJ will be a pavement pounder...not much oportunity to go off road. Jeep runs/handles good, at 60mph the rpm`s are a little over 2000rpm`s. Thanks for your help Boris

Boris, To determine if you have a locker or limited slip you will need to jack up both rear wheels off the ground and spin one by hand.

If you have some type of locker they will both rotate in the SAME direction. If you have an open differential (no locker or limited slip) they will rotate in opposite directions.

As Mike started to mention... If you have a locker or limited slip you will need both tires to be the same size or the locker will see the tire size difference as slippage and lock the axle. A locked axle on pavement will cause tire or drivetrain damage if you are lucky. If you are unlucky ...... worse things can happen

The way to tell if you have a locker or limited slip is to jack up both wheels and spin one by hand. If the wheel on the other side spins the same way, then you have a traction device. If the wheel spins the opposite way you have open differential.

You can't use a smaller tire on an axle with a locker or limited slip.

If you just have a locker in the back, then if you get a flat you 'must' use the same size tire or you will destroy the gears. This means swapping tires around if you use a smaller spare.

If the front is still open, then when you have a flat in the rear, you have to take a front tire off and put it in the back and use the smaller spare in the front where the open is or vise versa if you only have a front locker.

You should get that brake looked at. Locking up in the rear can cause you to do 360's faster than you can blink.

Mike

Boris wrote:

Go to a used commercial tire store. Ask for the skinniest tire the same diameter as your regular tires, compare height by rolling the sucker up against your tires. Try to get within 1/2", exact same size is best, unless you want to cook your diffs on the highway run to the service station (50 miles or more around here). Then ask for a used steel rim with the same bolt pattern as yours that'll fit the tire (actually kinda hard, they turned the shop upside down to find one). Setback prob'ly won't matter 'cause the spare's so skinny, but test fit the spare to be sure before purchase.

The one I got was for delivery vans of some type, 6 1/2" wide, with a highway truck tread; i.e., practically none. Spent $70 total and it weighs less than the 31x10.5s on my axles, close to a stock wrangler tire. So rear gate damage isn't gonna be a problem. And having a spare aluminum rim at home is a good thing.

The only way a smaller spare will hurt anything is if you have a traction device in the axle. If you have open differentials, you can even use the 'silly spare' that comes stock with some Jeeps.

Our Cherokee has open diffs and it came with a silly spare. After blowing a tire off the rim on a sand pit wall and finding out how useless that spare is, (can't use it with 4x4 'part time' either) we got a full sized one for taking off road with us. We still use the silly spare for space saving in the city though.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Thanks again Mike The rear left drum doesn`t lock under hard braking only in city driving and locks just before I come to a complete stop (2-3mph)...I`m thinking of going to Sears to pick up a floor lift, they have a 3 ton floor lift with 2 floor stands for $70...anything to watch out for? The spare will have to wait until I figure out the brake lock-up...you made me nervous! I have a Chilton Repair Book covers 1945-1987 Jeeps of course mine is a`88 so I don`t know for sure if `88 YJ have self adjusting rear drums like the `87...I`ll take the Jeep to a parking lot and try the self adjusting procedure.....10-15 stops in reverse, see if that will help. If not I will bring the Jeep to a brake shop....they can install the new emergency cables that I have too. Thanks again Boris