AMC-MJ Posted December 29, 2009 Share Posted December 29, 2009 My speedo reads 65mph@3,000rpm, tho i have no idea what tires or gears it's calibrated for. 1988 Comanche 2.5L 4spd manual D35 axle ? tire rack list's the tire size as P225/75R15 2WD / LT235/75R15 4WD. one of the Vintage tire sites list's a G78-15 2WD / F78-15 4WD. Its got ST225/70R15C tires on the rear P215/70R15 on front so i'm guessing it's set up for 28"-30" tall tires ? What gears did they put in them ? how do i find out whats are in there ? Whats the GVWR of these ? none of the data plates say anything, I did tag it today with a "B" plate 6,000LB's, that should be close enough. Mike Link to comment Share on other sites More sharing options...
Eagle Posted December 29, 2009 Share Posted December 29, 2009 The 2.5L 4-speeds came with 3.55 gears. The stock tire size was probably either 195/75-15 or 205/75R15. Those sources you listed are wrong. The XJs and MJs all came with P-metric size tires, right from the first XJ in late 1983, so the letter-series tires are flat out incorrect. And the largest tire the factory ever put on an XJ or MJ was a 225/75-15 -- and that was only with the 4.0L engine. Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 I was hopping to run a 235/75R15 or G78-15 so i could run an aggressive treaded tire, P195/75R15's ? or P205/75R15 's ? :fs1: WI's winter's ya know :wall: . . . Mike Link to comment Share on other sites More sharing options...
Automan2164 Posted December 29, 2009 Share Posted December 29, 2009 Yep, the tire size is a manufacturers suggestion, not rule... By any means... Rob L. :cheers: Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 195/75R15: http://www.tirerack.com/tires/TireSearc ... 5&x=38&y=5 205/75R15: http://www.tirerack.com/tires/TireSearc ... &x=30&y=10 These tires simply will not do. . . 235/75R15: http://www.tirerack.com/tires/TireSearc ... 5&x=20&y=0 G78-15: http://www.universaltire.com/truck-and- ... axion.html Now these tires will work nicely. . . Can the speedo be recalibrated to these tires ? or would i have to Regear it ? Mike Link to comment Share on other sites More sharing options...
Eagle Posted December 29, 2009 Share Posted December 29, 2009 I was hopping to run a 235/75R15 or G78-15 so i could run an aggressive treaded tire, P195/75R15's ? or P205/75R15 's ? :fs1: WI's winter's ya know You asked what the stock size should be. Don't get uppety because I told you. They make snow tires in those sizes. You can run 235s. Just be aware that they are oversized, the 2.5L 4-speed is a dog to begin with, so it'll be even doggier with those bigger tires on it. Don't go any larger than 235/75-15 or you'll have clearance problems in the front. Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 Sorry didn't know i was being uppity . . . I was grumbling at the winter n snow not the tire size . . .I searched the correct tire sizes 1 was obsolete the other was limited in tread design's . . . It's a rather peppy truck this is why i figured it had 3.73's or 4.10's or some thing as it wrap's 0-70mph rather quick way faster then my 6.5 diesel and that has 4.10's and undersized tires, factory was 235/83r16E 32" tho i went to 7.50-16D for winter 32.2" i went to 245/75R15E 30.5" for summer . . . EDIT: The diesel is a real gutless puke i wouldn't be shocked if the 2.5er out tows my 6.5er as well as out running it, my buddies 4.3L 4 spd auto with 3.42's n 30x9.50R15's out tow's and out runs my 6.5 . . . I think my 2.5L 4spd Manual get's up n goes rather well Myself, its got 225/70R15's on the rear right now n 215/70R15's on front topper n a bed full of rims n junk tires and it runs out Very smoothly n quick IMO. Mike Link to comment Share on other sites More sharing options...
Eagle Posted December 29, 2009 Share Posted December 29, 2009 The speedo can be recalibrated by replacing the drive gear in the transmission. Your truck feels peppy because the tires on it are smaller than stock. The 70 series tires are about an inch smaller than the stock 75 series. For example, a 2000 XJ Sport comes with 225/75R15 tires and a 2000 XJ Classic comes with 225/70R16 tires. They are the same size (diameter). I have an '88 MJ 2.5L 4-speed. It gets from point A to point B, but there's no way I would ever describe it as "peppy." Link to comment Share on other sites More sharing options...
freakjeep93 Posted December 29, 2009 Share Posted December 29, 2009 ive got a 4 cyl 4 speed and with p 225 /75 r 15s i can spin the wheels in 1st and 2nd gear no problem and it has lots of power. Link to comment Share on other sites More sharing options...
socal1200r Posted December 29, 2009 Share Posted December 29, 2009 Weird...my '88 MJ has the 2.5 4-cylinder with a 5-speed, 4wd, D35 rear axle with 4.10 gears, and doesn't seem to have any problems getting up to freeway speeds. It's also running 15x7 Jeep alloys with 31x10.5 Firestone Destination AT's, with WJ LCAs, so there's no tire rubbing on hard parts or fenders (unless I'm entering or exiting a steep driveway at an angle). When I first got the MJ, it had the stock steel wheels, with 235/75 Goodyear Forteras. They looked pretty decent, better than the 225/75 Michelins that were on there before. I'd say go for 235/75s, or at the very least, 225/75s. Your 2.5 should drive just fine with either of those sizes, unless your gear ratios are really low, numerically speaking. Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 It run's 65mph@3,000rpm in 4th gear so it's got some gear behind it for sure . . . It has no trouble running 0-70mph, it wrap's right up to 75-80mph before getting doggy by 88mph it's all done it stop's accelerating ! I had an 89' Ranger 2.9L V-6, 5spd n 3.55's i put 30x9.50R15's on it truck did just fine ran 0-75mph just and towed around 1,500lb's with out any trouble . . . So i would imagine a 2.5L I-4 n 3.55's no OD should do fine with 1.2" shorter tires, plus a 2.5L I-4 v.s. 2.9L V6, should have a bigger bore or stroke maybe both as the CID/Cylinder is larger = more low end grunt. 150/4 = 37.5Cid/Cylinder. 177/6 = 29.5Cid/Cylinder. Just a thought ? . . . Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 The 2.5L 4-speeds came with 3.55 gears. The stock tire size was probably either 195/75-15 or 205/75R15. Those sources you listed are wrong. The XJs and MJs all came with P-metric size tires, right from the first XJ in late 1983, so the letter-series tires are flat out incorrect. And the largest tire the factory ever put on an XJ or MJ was a 225/75-15 -- and that was only with the 4.0L engine. Your truck feels peppy because the tires on it are smaller than stock. The 70 series tires are about an inch smaller than the stock 75 series. For example, a 2000 XJ Sport comes with 225/75R15 tires and a 2000 XJ Classic comes with 225/70R16 tires. They are the same size (diameter). I have an '88 MJ 2.5L 4-speed. It gets from point A to point B, but there's no way I would ever describe it as "peppy." 1. you contradicted your self by saying only the 225/75's came on the 4.0L I-6, and using the 225/75 v.s 225/70 comparison. Now lets go with what you claim was one the 2.5L I-4 tires sizes. 2. 205/75R15: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes 26.8" tall . . . 225/70R15: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes 27.4" tall . . . Now in comparison to what i "HAVE NOW" to what "SHOULD" be there they actually got taller .8" taller. 3. there for blowing your theology of the 2.5 being doggy right out the water. . . Now compared to a 4.0L i'm sure the 2.5 is soggy but now compare the 2.5 AMC to the 2.5 GM n 2.3 Ford of the time frame you'll find the AMC was quicker, A lot quicker i have owned both the 2.5 GM and 2.3 Ford in reg cab short bed 2WD 4spd manual transmission truck's. Now i guess this is all opinion, but it seems as tho the majority of 2.5 owners are plenty happy with there performance.. . . EDIT: I'm going to run the mph/rpm calculator once see what that gives me. . . Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 225/75R15: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes 235/75R15: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes i used the same General AT2's for the 225/75R15's-235/75R15's so all 4 tires where of the same brand n model. 3.55 gears @ 3,000rpm: 205/75R15 = 67.4 mph. 225/70R15 = 68.9 mph. 225/75R15 = 71.1 mph. 235/75R15 = 73.2 mph. 3.73 gears @ 3,000rpm: 205/75R15 = 64.1 mph. 225/70R15 = 65.6 mph. 225/75R15 = 67.8 mph. 235/75R15 = 69.7 mph. 4.10 gears @ 3,000rpm: 205/75R15 = 58.4 mph. 225/70R15 = 59.7 mph. 225/75R15 = 61.7 mph. 235/75R15 = 63.4 mph. The 205/75R15 with 3.73 gears was the closest to what i witness on the speedo, so it very well could be set for 205/75's n 3.73's but as you can see the 3.55's are way off . . . Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 So i'm going from 225/70R15 = 27.4" to 235/75R15 = 29.1" would i be better off with the G78-15's those are only 28.5" ? 235/75R15: http://www.tirerack.com/tires/TireSearc ... 5&x=38&y=1 G78-15: http://www.universaltire.com/truck-and- ... axion.html there's the tires i have to choose from. . . Mike Link to comment Share on other sites More sharing options...
socal1200r Posted December 29, 2009 Share Posted December 29, 2009 So i'm going from 225/70R15 = 27.4" to 235/75R15 = 29.1" would i be better off with the G78-15's those are only 28.5" ? 235/75R15: http://www.tirerack.com/tires/TireSearc ... 5&x=38&y=1 G78-15: http://www.universaltire.com/truck-and- ... axion.html there's the tires i have to choose from. . . Mike Stay with the metric-sized tires, and go with a good 235/75-15. I like the Firestone Destinatino ATs I have, and WalMart has some really good looking Uniroyal Liberators and Goodyear all-terrains of some kind (can't remember the specific WalMart model name). Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 I prefer MT's, Super Traction's, Extra Grip's, and Swamper's . . . I like loud tire's, If i can't hear then i don't want them, i have looked at the Lib AT's and them Wrangler's at wally world, But i just don't think they are what i'm looking for. Firestone Destination MT's: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes Radial Mud rover's: http://www.tirerack.com/tires/Spec.jsp? ... mpare1=yes look up to spec . . . But i love them Biasply gripper's for the Snow . . . STA Super Traxion: http://www.universaltire.com/truck-and- ... axion.html "If they ain't howling i'm getting stuck" Mike Link to comment Share on other sites More sharing options...
Pete M Posted December 29, 2009 Share Posted December 29, 2009 BFGs ftw! http://www.tirerack.com/tires/tires.jsp ... mpare1=yes Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 29, 2009 Author Share Posted December 29, 2009 $148/Tire ! :eek: . . . May as well of gotten some TSL-Radail's. . . Mike Link to comment Share on other sites More sharing options...
socal1200r Posted December 30, 2009 Share Posted December 30, 2009 Those tread patterns look too aggressive for street use. I don't plan on taking my MJ off-road too much, certainly nothing like rock crawling or mud bogs, so an AT tread design is more than enough for me, and less expensive too. But looks like you have a pretty good idea of what type of tire you want, it's just a matter of what size. I still say go for the 235/75, and stay away from the letter-type tires. Link to comment Share on other sites More sharing options...
Pete M Posted December 30, 2009 Share Posted December 30, 2009 TSLs are not very road friendly. I don't buy new tires anymore for anything so I've developed an immunity to sticker-shock. :D They are all overpriced. Last set of 4 tires I bought were for the Liberty and they were like-new and cost me a little over 250, mounted and balanced. New they were like 150 per tire. Found a matching 5th with 75% tread for under 50 bucks a bit later. Sold the old unused spare for almost $50 too. time before that I got 2 brand new front tires for the Dakota with the R/T rims for all of $100 off ebay (got lucky and they were only an hour away). Used tires are da bomb as long as you're patient when looking, and thoroughly inspect before handing over cash. Also walmart is pretty cheap mounting/balancing. :thumbsup: Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 30, 2009 Author Share Posted December 30, 2009 I run them on the road they do just fine, Them old school biasply traction n grip tire's in them standard 7.00-15's 7.50-16's 8-19.5's 10.00-20's ECT and so along, really have a stand out look to them. :D But the Metric Radial MT's will last longer and ride smoother then the Standard sized Biasply Lugger's. :dunno: there about the same price the 235's n G78's . . . TSL's not road friendly ? which TSL's you running ? I had a 95' F150 XLT 5.8L V8 4x4 i ran a set pf 33x10.50R15 Radial TSL's never left the pavement i put 43K miles on them 1/4"-3/8" tread depth left but the 3rd E40D failed i sent the truck on its way. . . This truck i know weight's a good bit less they should wear longer. . .but then they'll be sorter n skinner which might make them wear faster but should go all of 35K+ miles ? Mike Link to comment Share on other sites More sharing options...
Pete M Posted December 30, 2009 Share Posted December 30, 2009 TSL's not road friendly ? which TSL's you running ? Mike SXs. mine are absolutely deadly on frozen pavement. :dunno: Link to comment Share on other sites More sharing options...
AMC-MJ Posted December 30, 2009 Author Share Posted December 30, 2009 Really ? i wonder if it was the lighter truck ? My F-150 Rarely needed 4WD in the winter it got threw most of the winter's just running 2WD, Truck got around great handled wonderfully . . . This my 5th little truck only the MJ and one 4x4 saw winter time. . .I had 2 rangers 1 2WD 1 4WD, 1 S-10 2WD and 1 Nissan 2WD, and now the MJ 2WD. . . I'm used to running 3/4ton aka C/K-2500's n F/D-250's n heavier . . . Mike Link to comment Share on other sites More sharing options...
Pete M Posted December 30, 2009 Share Posted December 30, 2009 I've noticed that heavy trucks can make even poor tires look good in the winter. My TSLs are the like the opposite of snow tires. I've owned worse though. Those Skorchers weren't fooling anyone. :D Link to comment Share on other sites More sharing options...
Eagle Posted December 30, 2009 Share Posted December 30, 2009 The 2.5L 4-speeds came with 3.55 gears. The stock tire size was probably either 195/75-15 or 205/75R15. Those sources you listed are wrong. The XJs and MJs all came with P-metric size tires, right from the first XJ in late 1983, so the letter-series tires are flat out incorrect. And the largest tire the factory ever put on an XJ or MJ was a 225/75-15 -- and that was only with the 4.0L engine. 1. you contradicted your self by saying only the 225/75's came on the 4.0L I-6, and using the 225/75 v.s 225/70 comparison. I didn't contradict myself at all. First, I didn't say that only the 225/75s came with the 4.0L. I said that was the LARGEST size the factory used. Second, I used the sizing comparison of the 225/75-15 versus the 225/70-16 to show the difference going from a 75 series to a 70 series makes. I chose that example because both were offered by Jeep on the 2000 Cherokee, and I have one of each parked in my garage right now. But that's for 2000, when Jeep offered 16" rims on the Cherokee Classic and Limited. They did NOT offer either 16" rims or 70-series tires on the Comanche -- ever. The point was that you have a truck that came from the factory with 75-series tires on it, and you are now running 70-series tires on it. Ergo ==> your tires are smaller than stock, which equates to the same thing as having more gear. If you want to make your comparison valid, compare the same nominal size between a 70-series and a 75-series. Take either a 205/70-15 vs. a 205/75-15, or a 225/70-15 vs. a 225/75-15. Link to comment Share on other sites More sharing options...
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