Anyone Running 305/55R20

[davez71offroad]

IM currently looking at putting new tires on the Tahoe and im between 305/55R20 and 285/55R20 tires on an SS silverado rim 20x8.5. Which ones would fit with a front leveling kit on a 07 Z71 Tahoe? Minor trimming is fine. Any pics of setups would be great. Thanks for the help. I am open to puuting spacers in that back if that helps fit the tires.

 

[InTruckDesign]

I am running them in a Nitto terra grappler, you may only have minor trimming if you keep the backspacing/offset as close to factory as possible. I have aftermarket wheels that are -18 offset with 4.5bs, I have the CCM 2.5"/1"(fr/rr) and had to do some minor to major trimming...all depends what your definiton of trimming is!?!?!?! I did trim some of the metal pinch weld behind the wheelwell liner on the back of the front tire area.

 

[davez71offroad]

The tires will be going on the Silverado SS rims. I have beend oing some research on the tires and some ppl are clearing them as i see you are. Im fine with trimming the plastic. I have already pulled the front air dam off. Can you get any pics of you wheelwells and the trimming you did?

 

[07warwagon]

I have 305/55/20 Nitto Trail Grapplers on my Burban with a Rancho 4" lift and trimmed some of the plastic wheel liner in the front driver and passanger wheel wells.

 

[davez71offroad]

Finally got everything installed and ended up going with CCM leveling kit and 305/55R20 BF Goodrich Tires.

 

[Mr. B]

Is the CCM kit just a front level, or does it raise the back as well?

 

[Zed 71]

Dave looks good. I wonder why you had less triming (a lot) compared to InTruck? I wonder what the offset difference is.

Mr. B the CCM kit raises the rear as well. On mine the rear was ~0.25" higher, barely noticable.

 

[davez71offroad]

Zed, I had trimmed some when I had my old tires on the truck so that is probably the reason but i will say that th offset on the rims is perfect for this setup. Both the front and the rear are sitting at 40 inches.

Has anyone had the stablitrac light or the ABS light come on after installing the leveling kit and tires cause mine come on when I got home last night.

---------- Post added at 02:20 PM ---------- Previous post was at 02:18 PM ----------

IN Truck, Did you have problems with your Stablitrack and ABS lights when you went to those size tires cause I have almost the same setup as you and both lights are flashing?

 

[Zed 71]

I have had no problems with the lights. Might be a sensor connection issue located at the front struts. Check those first. Also check if the tires rub any wire harness at full lock. That has been an issue for a few folks.

 

[TREYR8D]

Dave, ur truck looks friggin awesome!

I'm also in between the 305/55 R20s and 285/55 R20s. I've been leaning towards the 285s for a couple reasons.
1) i heard the fuel milage will take a noticable hit with the wider tires, can you give any insight to this?
2) the required trimming would be less since the actuall sizes are 305=>33.19" and the 285=>32.28" for the Nitto TGs. BFG lists yours as 33.4"
3) I really didnt want the tires to stick out past the fenders. Wheels i'd get are +18 offset w/ 5.75 BS, i think stock GMs are around +35 which is maybe 5.6" BS (maybe someone knows for sure). how close are your tires to being flush with the fenders?

All in all considered, the 305s i think would look better, so if my thinking is wrong on those three points, i'd want to go with the 305s. Funny thing is, i think they're actually $20 cheaper/tire. Probably because of the load range rating difference.

Thanks

 

[UofMZ71]

looks great!

 

[davez71offroad]

Trey, I was hesitant like you between the 285's and 305's. I just went a head and put the 305's cause I loved they way they looked. I couldnt be happier with the turn out. I'm not sure excatly the backspacing on the wheels I have but I know if you run the stock 20 you wont trim that much and even with the 305's the dont stick out the just fill the wheel well up better. Your going to have to trim a little bit of plastic with the 305's and I pulled my Air dam off but I think it makes it look better any way. As far as gas millage I'm not to sure yet what I get but will keep you informed. I posted some better pictures check them out.

 

[TREYR8D]

Well, from what i found on a quick google search, the SS rims are 22 mm offset, with an 8.5" rim, that's 5.116" backspacing. So i guess the 18 mm will only make the 305s stick out 4 mm more. That just leaves the fuel mileage question. I currently get around 19 on interstate/highway, closer to 17 with more "city" driving. I'll assume i'll take a small hit from a little bit of lift, but if the tires dont add much more, i'm goin with the 305s.

 

[InTruckDesign]

If your abs/stabilitrac lights are flashing or are on constantly then I would definetly check all wiring harness', mine would come on when taking a sharp corner at a slow speed, now that I am tuned for the tire size difference they have not come on at all.
Your truck came out nice, biggest reason why you did not have to trim as much is due to rim offset. Your rims tuck a little bit more than mine, though that may change soon as I am looking at going to either stock 20's pc'd black or SS wheels like yours, but again pc'd black.

 

[Zed 71]

Well, from what i found on a quick google search, the SS rims are 22 mm offset, with an 8.5" rim, that's 5.116" backspacing. So i guess the 18 mm will only make the 305s stick out 4 mm more. That just leaves the fuel mileage question. I currently get around 19 on interstate/highway, closer to 17 with more "city" driving. I'll assume i'll take a small hit from a little bit of lift, but if the tires dont add much more, i'm goin with the 305s.

Your mileage will definitely take a hit. I was getting close to the mpgs you stated above. When I changed to larger tires (285/65/18s on stock rims) with the level kit, my mileage really went down - ~14 city and ~16 highway. Keep in mind that I changed to Load E mud terrains and did not get the speedometer correction yet.


If you get a lighter load tire and just all terrains (like the BFGs), you should get better mileage than me.

 

[davez71offroad]

InTruck, What did you have to do to get your Tahoe tuned for your tires? I reinstalled My Hypertech programmer and put in the different tire size and the lights still flash. I was getting 17 highway and 15 city before the install.

 

[InTruckDesign]

I run EFILive and am a BlackBear tune dealer, so to tell you what was adjusted does no good with your Hypertech, really need a custom tune to properly correct for tire size. Sure your speedo may read correctly, but you still need to adjust shift times, speeds, pressures, along with torque converter lock up speeds, etc. they all play a part in the big picture.

 

[TREYR8D]

Yea, i have noticed that MTs vs ATs can really make a difference. I know i gained a couple MPGs back on my wrangler when i switched from the GY MTRs to the BFG all terrains in the same size. Probably due to rolling resistance of the tire.

So with the load rating, in the Nitto TGs at 305/55R20, you can get them as XL, extra load, or load rating E. I understand that load rating E has a 10 ply sidewall, but what does the XL rating have. From what i've found with pricing, load rating E is more expensive, so one would assume it has the higher sidewall ply....I'm not planning on hauling anything heavy or pulling anything, so i'm pretty sure i dont need the load rating E, am i correct?

 

[InTruckDesign]

I run the E-rated Terra Grapplers on my tahoe and they have 30k on them and easily have another 30k left, and I chalk up the excellent tire wear to the E rating...remember these tahoes are heavy bricks.

 

[TREYR8D]

yea, one would assume that if the truck is in the load range of the tire it uses it would be ok for tire wear as long as you use the proper inflation.

I wanna see some pics of ur truck InTruck, sound amazing from ur sig