RPM's at 60 mph

[firehawk]

Anyone on here have a stock XJ with the 4.0L, AW4, and 3.55 gears on stock sized tires?:confused: Reason I ask is I am kicking the idea around about regearing this summer/fall. Right now on 31's I'm running about 1700-1900 rpm at 60 mph in OD. That is below the powerband for the 4.0L. I can't remember what mine ran at when I first got it.

I'm thinking about going with 4.10's as I think 4.56's would be a bit too low for me using my Jeep as a DD. I'm going to have to replace the MT's this fall and while I'd like to go with 33's, I DON'T want to have to do any trimming so I'll probably settle on a set of 32's.

[Mudderoy]

I'd like to know this too. I'm guessing 2200 rpm.

[Melissa]

Mine runs right at 2000 rpm at 60 mph

[firehawk]

Mine runs right at 2000 rpm at 60 mph

Are you running stock sized tires? Which I think are 245-70-15, not exactly sure though.

[Melissa]

Are you running stock sized tires? Which I think are 245-70-15, not exactly sure though.


They are on my stock wheels, they are 235-75-15's

http://i730.photobucket.com/albums/ww305/melreese83/numbered%20pictures/HPIM0368.jpg

[Audio222]

I have 31"tires, auto trans and 4.56 gears on a daily driver and I turn about 2400-2500 rpm 65-68 mph. I haven't changer the speedo gear yet.

Mine was a dog on 31s and stock 3.55. I wish I would have went 4.88 instead.

[Mudderoy]

They are on my stock wheels, they are 235-75-15's

http://i730.photobucket.com/albums/ww305/melreese83/numbered%20pictures/HPIM0368.jpg

Outer Diameter: 28.87 "
Section Width: 9.251 "
Rim Size: 15"

[weaselguys]

215/75r15 is the stock tire size on a cherokee.When I bought my 94 used it had 225/75r15 (car) tires on it I upgraded to 237/75r15's and my rpms didnt change much still at about 2200-2400 at 70mph and about 2500 at 75mph.My 2001 has 31x10.50's and 3.55 gears and runs 2200 at 70mph .I dont know where the power curve is at for the 4.0 but with 31's and 3.55's I have no lack of power,I can hmmer it and pass what I need to and I can run 85+ with no problems.Mileage is where the real question is I went from 22-23 down to 19 going to 235's and with my 31's my best is 17.8 where does the power /economy curve fit here.Beats me

[kennzz05]

some have said near 3000 but i find that hard to belive ive read on naxja that you get better mileage at 3k than2k but with over 300k on my motor and regular trips once every other month from the east coast of fl to the west and back im not running my mtr in that range to find out i try to keep it around 60-63 mph which is a hair below 2k i run 285x75x15 which are just shy of 32s x11.5 best ive ever gotten was18 mpg

[muddeprived]

215/75r15 is the stock tire size on a cherokee.When I bought my 94 used it had 225/75r15 (car) tires on it I upgraded to 237/75r15's and my rpms didnt change much still at about 2200-2400 at 70mph and about 2500 at 75mph.My 2001 has 31x10.50's and 3.55 gears and runs 2200 at 70mph .I dont know where the power curve is at for the 4.0 but with 31's and 3.55's I have no lack of power,I can hmmer it and pass what I need to and I can run 85+ with no problems.Mileage is where the real question is I went from 22-23 down to 19 going to 235's and with my 31's my best is 17.8 where does the power /economy curve fit here.Beats me

225 and 235's are the only stock sized tires i've seen on xj's. I haven't seen 215's yet. When i bought my tj back in 2002, there was a yellow xj a couple cars down (brand new) with 225's.

[N1TZU]

Hello firehawk, I had 235x75Rx15 before the lift and new tires. At 60 mpr mine ran about 2200-2400 rpm's.... Bob....

[weaselguys]

Check the panel on the drivers side door of your xj ,both of mine list 215/75r15 as the stock tire sizethat should only be slightly smaller then 225's .If anyone has 225/75r15's on they could tell us what the proper rpms are for 60 and 70mph.My 94 speedo is still setup for the stock tires,my 2001 has been set for my 31x10.50's and runs 2200-2250 at 70mph.