Flatlander

Did a search, no luck. I have a 95 Cherokee 4.0, all standard and have just replaced the rear 225/70-15" rear tires only with 235/75-15". The front still has the OE 225/70-15's on.How hard on the transfer case, trans. etc. will this be when in 4H on wet/slushy/icy paved roads this winter and should I match them up? Hoping to hear from someone who knows for certain what kind of harm(if any) can be done with this particular vehicle/trans/case. Thanks in advance!

CheapCherokee

dont run it in 4x4 with the mismatched tires. thats about a 1" difference in diameter between the two. this would put some serious strain on the drive train, mainly the axles, driveshafts and transfer case.

Cherryokee

The difference is so small it's negligible. It will not damage your drivetrain.

CheapCherokee

actually what tcase do you have? if you have a 242 you could probably run it in full time 4wd and not do much damage.

Flatlander

Thankyou for the replies. No idea what case I have but it shows 2H, 4H or 4L on the shifter left of the AOD floor shifter. (?)
Cheap may be right about the size diff tho, it is at least an inch taller in the rear now and I've had to adjust the headlights to compensate.

CheapCherokee

yeah you have the 231, no full time 4wd. your technicaly not supposed to run part time (what your 231 has) on the street anyways, but in the snow or watever it might be benificial, but definatly not with mismatched tire sizes

djb383

OE tires were 225/75/15, no? 235/70/15 are virtually identical OE diameter.

mwdouglas

he has 225/70/15's in the front with 235/75's in the rear that will put a strain on the tcase chain in 4wd the front and rear tires will be rotating at different revalutions and will eventually bust a gear in the axle and or chain in the tcase.
as far as op you need to run equal size tire front and rear

Flatlander

So, I'm getting that this is old-school 4x4 and should not be in 4H on any paved roads, even with equal diameter treads. Is that correct?

rustcollector

Just for my thoughts for what its worth.
The radial tyre figures are as follows.
The 225 and 235 dimensions are the nominal tyre width in millimetres when correctly inflated.
The 70 is the aspect ratio. This means the tyre sidewall height is 70% of the tread width.
The 15 is the wheel rim diameter.
Basically you have a tyre that is 10 mm wider. Your sidewall will be 70% of this so will be 7mm taller. Therefore the tyre will be 14mm taller approximately.
So a little over 1/2 an inch. If you had permanent 4x4 it would wreck the trans on tarmac roads. In 4H with the part time system only engaged on slippery surfaces it will do it no harm. But remember to disengage the 4wd and return to 2H when you get on clean tarmac.
Not trying to preach, just sharing what I know from 24 years in the auto and tyre industry here in the UK.

freegdr

4wd should never be used on any surface that offers great traction potential or hard paved road,with matched or unmatched tire when case is direct drive . OLD SCHOOL

Flatlander

Thankyou rust. I'm confused aboot the repeated reference to "part-time" 4H as my vehicle makes no reference to part or full-time 4H or 4L, just the three basic manual shift positions(while A-Transmission is in nuetral) for the transfer case.
Conditions I'm concerned with are 60% bare asphalt, 40% slush, dirt/sand and ice at 40ish mph road speeds.

Flatlander

Thanks free. That's what I was afraid of. However, I thought only 4L was direct drive? Good to know.

freegdr

i have a different tc

djb383

The OP says OE 225/70/15 in the front......all I'm saying is OE is 225/75/15, not 70. I agree that 2 different diameters front/rear would be fighting each other, causing unnecessary strain/load somewhere in the drive train.