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What size Tire with a 4" Lift?

K5-Kelly

K5-Kelly

1/2 ton status
Joined
Jan 1, 2008
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Location
Beautiful British Columbia
Okay I'll admit it.....I hate doing things twice, or for that matter three times. Last October we were taking our 91 K5 Jimmy down to see Ozzie Osbourne and traffic was backed up and stopped. After 15 minutes of waiting with no movement and not wanting to be late for the concert, I drove over this fat, tall median and I bottomed out the trailer hitch hard and that's when I decided to put in a lift kit. Last Christmas I bought a 4" Rancho lift kit with new rear springs as our's were sacked and I hadn't installed it yet cause I've been busier than I thought it would this year but as we speak I'm doing it now. Isn't that what vacations are for? Yes the woman is pissed but I reminded her that when we met I was a motor nut and my vehicles are the other women.
Okay so I have a winch bumper with an older Warn and I have a brush/grill guard and I was thinking about upgrading the front and rear bumpers with something from the blazen off road people. I use the truck pretty much all the time when the weather's crappy and I use it for hunting/fishing and I drive her in the winter. We actually drove it from Vancouver to Los Angeles last year as it fit all of our stuff and the A/C blew cold.
So what I want to know is based on all of your experience, whats the best tire and wheel combo and which size tire is best suited for our driving style? Keep in mind in rains up here a lot! I was thinking of going to a 17" wheel, I dunno what do you think?
 
What size tire can you run? You can fit 32's with no trimming, anything bigger than that will require fender clearancing. Check here.

As for wheel size, on 30"+ size tires the bigger the wheel the better.
 
Loaded question. If your in love with your fenders I would say a 33x12.50 max and leave your sway bar on. If your willing to cut a little you can get away with 35". If you aint skeert you can fit skinny 38's on skinny wheels and loose the sway bar. Thats what I had on my blazer years ago before I retired it. It still rubbed the tops of the inner fenders, but thats smooth and dont cut up your tires. It was a 4" rancho lift and cut fenders and no sway bar. 38's rubbed the inner fenders, 35's my shocks/bumpstops limited out first. I cut the front fenders just below the marker light clean off (the fangs) the rear of the front fenders were cut back to the inner fender and tapered up halfway to the curve in the opening. the rear fenders whre cut 3" forward and rear and also tapered up.
 
I'd hate to cut these fenders as the whole truck is solid and straight. I've had trucks in the past where I've done some trimming and it works.....but I really don't beat the truck to warrant it. My buddy who's a lot younger than me has a huge lift on his K5 and he took his sway bar off and it makes for an interesting ride. Granted he can go where I only dream of but on the highway there he ages quickly.
 
I'm running 33x12.50 15's bfg tires with a 10 inch rim with out cutting any fenders and no rubbing anywhere.

Mike
 
On my '89 Blazer I had 35" tires on with the 4" lift. Looked great and no rubbing. That's as big as you want to go with only 4" lift.
 
For your driving style as you described. I think 12.50 x33"X15" would work fine. They will fit for sure without any trimming.
IMO stay away from 17" wheel or larger unless you are just going strictly for looks.
The larger diameter wheels usually mean tires with skinner side walls. That reduces sidewall flex and usually causes less traction off road or in winter snow.
Gears and drive train should also be considered. 33" tires will work fine with 1/2 ton suspension without worrying about breakage. 33s will usually work fine with most the standard gear ratios. Larger than 33" with gear ratios less than 3.73 will put a lot of stress on your drivetrain especially if you have a 700r4 trans.
I have tried both 33 and 35" tires on my 89 K5 with 4" lift, 3.73 gears, 700R4. Personally I like 33s the best. I have lockers front and rear and beat on my truck hard. She is also my Tow rig, hunting/fishing all around use vehicle.
35s looked better but were too tall for my 3.73 gear ratio. My k5 did not like to run in overdrive on the highway. Also I did not like the way it towed with the taller tires.
Offroad i could tell no difference between the two sizes. except 35" put a lot more stress on U joints and other drivetrain parts. I gladly gave up a little ground clearance for less drivetrain stress and dependability.
I don't run a sway bar. I don't really need one my truck handles fine without it.
They are not hard to remove or install. My advise to you is to try it both ways after you get the lift on and see what you like best. Rancho lifts are pretty stiff. My bet is you will like it better without the sway bar.
 
33's are your best bet in my opinion. i would stick with 15in rims.
 
Thanks for the input and in talking to some of the locals they are all leaning towards 33x12.50x15. Seems like that's what I'll be going with as I really don't want to go and get 35's and end in the end having to replace them with 33's. Yesterday while I was in the tire shop a guy came in with a set of 5 barely used 35x12.50x15's that he wanted to swap down to 33's and it was tempting. Also thanks for showing me the thread regarding all the rigs...great info, So the question now is which tire, the BFG All Terrains or something else?
Kelly
 
IMO cant go wrong with BFG AT KO. Good tough tire in the dirt, rain, snow, ice, and all around driving. They also wear well and last a long time.
If you want a tire that does not cost as much as a BFG AT. Check out General AT2 tires. Very similar to BFG and cost less. My highway/summer tires are the general AT2. I really like them. They are every as bit as good as my old BFGs. Have been running them for 3 years. They are wearing very well and get great traction on or off road.
 
Okay the lift worked out pretty good except the drive shafts are too short and the front drive shaft is now best friends with the y pipe. I really expected it so I allowed for it in the budget. Right now the tires seem like the most easy thing to do in this little mini project and the 33's look like the way we're going. Looks good so far
 
I am currently running 36" Iroks with a 4" lift and no front sway bars or shocks. I only rub at full flex. So it the variables are different for eveyone. Depends on your rim width, tire width and rim backspacing.
 
If your not planning on really flexing the truck, you can go with 35's. Your tranny will feel it though if your running 3.73's. When i had the '88 with 35's and a 4inch lift, i only rubbed during extreme flexing and that's after i took off the swaybar.
 
Hmmmm, really.....I thought about going with 35's but my driving habits are really tame as compared to my earlier years. Recently I took my girlfriend wheeling and we were are talking about mild BC logging roads. We got to a point where the road was cut into the side of a small mountain and there was a big drop off and she won't look over the side which was a great view, where as when I was younger that would be a paved super highway. I showed her the deactivated logging roads that I would go down if I were hunting or fishing with the buddies and that I would probably drive down a goat trail if it looked interesting enough. That's when she said "Do it and I'm walking", with out missing a beat I replied "Not for long when that bear finds you"
 
Drive line vibration

Okay the truck looks great and it's a lot nicer to drive as the old springs were sacked. It's actually more like a 5"-6" lift as compared to the original wore out suspension. The first time my girlfriend went to get out of the truck she kinda fell out because the ground is that much further away.
But now I have a nasty vibration coming from the rear drive shaft. When I took it in to get the shafts extended the drive line guys said that they couldn't balance the front because the splines were wore out. I knew it was making some noise prior and when I had a look at it you could see it was no good. So on the front we put a new drive shaft and u joints and it clears the y pipe better. But on the back the angle was too great to have u joint reliability and I've blown a few u joints on my other projects and just prior to this my buddy actually broke a u joint and busted the knuckle on his 6" lifted Chev. Bottom line it's not a good time.
So with this in mind I had them install a CV joint in the top of the driveshaft. You can see that with this set up I could almost go with another 6" of lift if I wanted to. But I have to remember this is my daily commuter. But now I have a nasty vibration at low speeds and it goes away or becomes less noticeable on the highway. The driveline guys say I need another 3 degrees of shim (In addition to the 6 degree shim) on the rear axle to make this go away. I looked around but nobody makes a 9 or ten degree shim. Another guy recommended lowering the transfer case. So my question is, What's the best way to tackle this problem?
 
With a CV joint on the rear shaft you should have the pinion pointed straight at the t-case output. There is usually no need ot lower the t-case on a K-5. Some of the vendors on here will make you a shim with any degree you need, do not go to stacking shims to get the right angle on the rear axle. You might try diy4x.com or jkwoffroad.com for the parts you need.
 
If you are not doing any hard off roading I would go ahead and try lowering the xfer case. To see if that works. It is a simple job you can do in a 1/2 hour with a jack and a wrench.
The only disadvantage to lowering the X-fer case. Is you loose maybe 1" ground clearance, and if you beat your truck real hard the bolts can crack the frame at the cross member. But for mild to moderate wheeling you should be fine.
I have a 4" lift with 6* shim on the axle. I and lowered my Xfercase to get rid of a vibration @ 40 -55 MPH. It works fine for me and got my DL angles almost perfect. Been that way for many years with no issues. Still an running the same NEAPCO u joints.
I did re-enforce the frame at the cross member because I beat on my truck pretty hard and its locked front and rear. The small loss of ground clearance has never been an issue.
 
if it were me i would just reshim the rear axle. lowering the t-case is another option i myself wouldnt do it but to each their own. jkw off road might be able to make you some shims with the degree you need.
 
I agree with jms. Just lower the tranny. See if that stops the vibration. If it does and you later decide to re-shim the rear, you only lost 30 minutes of your life. It's a free deal because your moving the spacers from the top of the frame to the bottom. All three of our trucks are setup that way without any problems. You just have to retighten them every so often.
 
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