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Tires for the 94+ Ram: WHAT FITS?
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size calculations - From the Miata Net garage page
Tire Size calculations - from the Powerdog Industries, Inc. site
Gear and tire size calculations - on the 4Lo.com site. Other useful 4X4 info here too!
Subject: Re:[RAM] 4x2 maximum tire size
Date: Thu, 05 Feb 1998 10:27:15 -0700
From: "Devin S. Olson" <firstname.lastname@example.org>
< .Does anyone know the maximum tire size I can fit on my 1997 CC Short Bed
< 16X7 Chrome Steel Rims?
If you go with anything larger than a 31 x 9.5 x 16, you will have "rubbing" on your front tires when in tight turns. The problem isn't really vertical (you can fit 33s in there w/o a lift), but is tire width on the stock 7" rims. If you had 16X8s or 16x9.5s, you could probably get a 10" tire in there, but you would still have some mild rubbing.
Devin S. Olson
Subject: Re: DiRT: tires?
Date: Mon, 31 Aug 1998 19:31:45 EDT
In a message dated 98-08-31 14:22:03 EDT, you write:
> I think I remember your saying that you know a guy with a 2wd and
> 255 85 16 tires and he uses a coat hanger on the plastic so they don't rub.
> Does your spare fit underneath the bed?
he has 245-70-19.5 tires and they required tying back the trailing edges of the inner fenders. These tires are 15.75" loaded radius compared to the 255-85 with 15.25" radius. You probably won't have to do anything to get 255s to fit.
My plan is to buy a set of commercial 245/70/19.5`s. This tire and wheel
combination is also 33", and has a much
better load rating than the LT models. Will a 2WD Ram 2500 fit 33" tires?
Date: Sun, 10 Jan 1999 21:35:59 EST
A local fellow has this combo, and all he had to do is use coat hanger wire to pull the rear of the front inner fenders back for more clearance. He wrapped the wire around the body mount behind the front wheel.
Subject: Re: Max tire size
Date: Wed, 24 Mar 1999 23:58:24 -0500
From: "Fred Backhaus" <email@example.com>
> What is the largest and widest tire I can safely put on my
> 2500 2WD with stock 16x6.5 rims??
I have a 96 4x2 club cab, when the 245/75/16 stock tires wore out i replaced them with 255/85/16 dunlop radial rovers, which fit on the stock rims. these tires have a great ride, and the load cap works for me. i currently have 22,000 miles on this set of tires and they show little wear. these tires look tight on the front, but i have had no problems with rubbing, and being 33" tires they look tough on a 2 wd. just remember that this is a tall tire not wide, if you go with a 265/75/16 this tire is tall(32") and wide(which may have a rubbing problem).
Stock height: 265/75R16 (this is the stock tire size).
Probably OK: 285/75R16, 235/85R16, 255/85R16, 32/11.50-16.5
With a 2-3" lift: 33/12.5-16.5, 315/75R16
With a 4" Lift: 35/12.5-16.5
Reports from owners:
From: "Jason Eberhard" <firstname.lastname@example.org>
Well technically I have 33's on my stock 16x7 rims. I have 285/75 16's mounted on the stock chrome rims and they measure 32.8 according to BFG. They are not as wide as 12.5" tire they are only about 11.5 at the widest point. I have over 55k on these tires and have not had a problem yet.
Reports from owners With Lift kits:
From: Keith Felton <email@example.com>
'96 360 4x4 CC SPORT, Procomp stg2 3" lift, Alcoa 16x8 with:
34x11.5x16 Mickey T Baja's that are actually 34.2" diameter. Most 35's vary between 33.5 and 35''
As for rubbing, I have the Mopar extended splash guards, and they rub very lightly on full lock on the inner edge.
Subject: DiRT: Tire Presures
Date: Tue, 01 Sep 1998 15:50:54 -0500
> I have BFG Radial All-Terrains 265\75\16 on my 1500 4x4.
> Everyone I speak with has different ideas on what pressure I should run.
> SO fellow Rammers, what do you think?
Without load or towing, I run 42 rear, 50 front. Same tire.
6.5x16" steel wheels - 1994-2000 ST/SLT, 2001 ST
8x16" Forged Aluminum heels - 2001 SLT
Aftermarket Wheels and/or lifts:
I left off the last post my spare just barely fits the frame. Dunlop 255/85R16
Radial Rover RV's
I have Cooper Discoverer LT 255-85-16. They fit the wheels and wheelwells fine and I believe they are about 1/2 inch or so taller than the Dunlop, also a bit narrower. They are quiet and wear well and the spare fits if it is has some wear. A new tire with no travel time is a bit too tall to fit between the frame rails properly. For that situation, I put in 2x2" spacers on the H crossmember so the tread was below the frame.
Re LT tire Pressure:
truck tires have a max pressure for full load carrying ability. That presure is too high for good tire wear when the truck is empty. The tires will wear out in the center of the tread. You can see what is proper for your use by running the truck with dusty tires over a sheet of paper and see if you get full tread pattern. If you get contact on the edges, pressure is too low, If contact is center and the edges are indistinct or not seen, pressure is too high.
My 255-85-16 tires are rated D for 3000 lb (note this is almost the 3042 lb that corresponds to an E rating in the smaller 245-75-16 size) at a pressure of 60 psi. I run about 54 lb in the front (diesel) and 46 in the rear with some stuff back there.
Subject: Re: DiRT: tires?
Date: Fri, 28 Aug 1998 21:20:55 -0500
From: "Carl D. Taylor" <firstname.lastname@example.org>
I just put 255/85R16 Dunlops on my truck Radial Rover RV. I wish they were a little wider but they look good and no problems reference the suspension.
My speedo was 2mph slow with stock tires by GPS new tires are 2.5-3mph fast same GPS used to check them. So I won't change the speedo.
Carl 96 BR2500 4X4 Cummins 3.54 Aut
3500 2WD, 4WD
LT235/85R16E is generally agreed to bew the maximum size without spacers between the wheel rims, but brands vary in width - max section width is 9.4".
Subject: Re: [RAM] FAQ somewhere about tire sizes?
Date: Tue, 08 Apr 97 08:46:00 PDT
From: Stephen D Belt <Stephen_D_Belt@ccm.ch.intel.com>
> Does anyone have a 1500/2500 vs. 4x2/4x4 vs. Wheel type vs. Tire size
> chart worked up yet?
I don't know of anyone with 4x2 info, but I'm going to provide the tire
chart from my Dick Cepek catalog that shows 4x4 info:
305/65R16 fit stock vehicles
31/14.50 fit with a minor fender trim (may not be necessary on 2500)
Q78-15 fit with 2/3" (2500/1500) suspension lift
36/16.50 fit with 2/3" (2500/1500)
suspension lift and serious
15/36 fender trimming or body lift
As for wheel sizes, 16" and larger wheels fit the 2500s. 15" and larger fit the 1500s. I recommend wheel widths in the 8-10" range for most of the tires list above.
1995 2500HD V10 4x4 -- Phx, AZ
Q: Does a taller tire interfere with the ABS?
I have had no braking problems with the four wheel ABS and 33" tall 255/85R16D tires. The ABS cycles normally on wet or dry pavement, snow, and gravel. The ABS has also helped keep the truck straight on a steep, muddy trail when I found too late that the transfer case should have been in low range.
Date: Thu, 15 Jan 1998 22:47:45
From: Mike Demski <email@example.com>
I often get asked the question: "Does your 4wheel ABS work now that you
put 35" tires on your Ram and had the R&P changed from the stock 3.54's
We finally got some more snow to cover the streets around here (been a mild winter :-( thus far) and I took the Ram out to test the ABS in slippery snow and ice.
I once again tested the ABS in 2wd and 4wd operation, mostly at speeds below 30 mph due to the side street speed limits, and it worked just fine on each activation. I can tell no difference from when my Ram was stock and in every case it kept the truck tracking straight as an arrow. I gave the 4wheel ABS a very good workout and she's working like a champ.
Mike Demski - firstname.lastname@example.org
96 Ram 1500 4x4 CC SB 360 - http://www.wwnet.net/~mdemski/rampage.html
The consensus from many who have installed larger tires on ABS equipped trucks is that larger tires have no effect on ABS operation. There have been scores of postings to this effect on the DiRT, RTML,Cummins, and Turbodiesel lists. Dave
1998+ Rams do not use a speedometer gear to determine road speed, the rear axle ABS sensor provides speed information. Because the PCM has a limited number of possible tire sizes, the speed often can not be corrected for larger or smaller tires. An aftermarket speed converter is the best option for those who must have correct speed readings. NOTE: Vehicles equipped with four wheel ABS may experience fault codes if a speed correction adapter is used. The indicated speed difference between the front sensors and the rear sensor may set an ABS fault code.
Some of the factory tire sizes and revolutions per mile are listed in TSB 26-11-99.
Some Standard Tire Sizes and Specs
LT245/75R16E - 3042 lbs @ 80 psi
LT265/75R16E - 3415 lbs @ 80 psi
LT215/85R16D - 2150 dual/2335 single @ 65 psi
LT215/85R16E - 2470 dual/2680 single @ 80 psi
LT235/85R16E - 2778 dual/3042 single @ 80 psi
BFG Mud Terrain
rim width section width tread width height
LT225/75R16D 6.0-7.0 8.9 7.0 29.5 2335
LT235/85R16E 6.0-7.0 9.3 7.3 32.0 3042
LT245/75R16E 6.5-8.0 10.1 7.6 30.6 3042
LT255/85R16D 6.5-8.5 10.5 7.9 33.3 3000
LT265/75R16D 6.5-8.5 10.7 8.4 31.7 3042
LT285/75R16D 7.5-9.0 11.8 8.9 33.0 3305
33-12.5-16.5RD 8.25-9.75 12.6 9.8 33.0 2930
35-12.5-16.5RD 8.25-9.75 13.0 9.8 35.0 3385
BFG All Terrain
rim width section width tread width height
LT225/75R16D 6.0-7.0 8.7 7.2 29.4 2335
LT235/85R16E 6.0-7.0 9.2 7.1 32.7 3042
LT245/75R16E 6.5-8.5 9.5 8.0 30.6 3042
LT265/75R16D 6.5-8.5 10.3 8.6 31.8 3042
LT285/75R16D 7.5-9.0 11.5 9.2 32.8 3305
LT295/75R16D 7.5-9.5 11.6 9.5 33.4 3415
33-12.5-16.5RD 8.25-9.75 12.4 10.0 32.8 2930
35-12.5-16.5RD 8.25-9.75 12.5 10.0 34.6 3385
Dunlop Radial Rover RV
rim width section width tread width height
LT235/85R16E 6.0-7.0 9.1 6.9 31.6 3040
LT255/85R16D 6.5-8.0 10.4 8.0 32.7 3000
33-12.5-16.5RD 8.25-10.5 12.3 9.5 32.5 2930
Wheel Rim Width Vs. Offset for Rams
Subject: [RAM] Rim for Rams
Date: Fri, 16 Jan 1998 08:19:06 -0500 (EST)
Rims should maintain the same centerline no matter the size. This means that if the offset is 2", it MUST remain 2". In other words, if the backspace = 4" on a 6" rim, you will need 5" on an 8" rim.
While this is the ideal, it isn't always possible. (There is only so much room to the inside of the wheelwell.)
So, you try to get as close as possible. The Rams seem to do well with a backspace in the 4-5" range in terms of fit. While this is close to optimum for an 8" rim, it starts to place more and more stress as the width rises. A 10" rim would most likely be perfectly fine in all respects. However, a 12" (and the tire that would carry) is starting to place the centerline of the wheel beyond the bearings.
It's up to you if you want to go that large, but I wouldn't expect to be able to use the truck to it's limits without doing damage. If you're just driving it around empty on the road, it should be fine, but add a trailer or large load, and you are adding stress the bearings were not designed to handle. They might do just fine, but it is a gamble.
the RamHack thinks that 10" is the largest you should go if you use the truck hard.
|From: Dizzy <email@example.com>
Truck: 1500 2WD with a Dick Cepek 3 1/2" lift
Tires: BFG 33 x 12.50 x 15 Radial Mud Terrain's
Wheels: Weld "Typhoon" 15x8 rims with a 4 5/8" backspace.
Lift includes new upper arms and a one inch spacer on the front. 1.5" blocks were used for the back. I haven't taken it off road but on the street I get a full turn both left and right without any rubbing.
KI4CY's (Dave Fritz's) 255/85 BFG MT's on a
'94 2500HD 4X4 Deisel Ram
Note: 2" lift sits 1" taller with camper and Reunel bumper/ Warn M12000 winch.
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A look at various tire sizes
Lined up in both pictures from Left to Right are:
BFG255/85R16MT, Dunlop 255/85R16 Rover RV, Goodyear Wrangler 245/75R16 AT, BFG 235/85R16 AT.
The Goodyear (Ram OEM tire) on the F250 was jacked off the ground for comparison.
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This page was edited on: May 3, 2004