New 275/70 R18 Bfg All-terrain T/a Kos

maffbr01 · February 2, 2011

After a few months of research, as well as an unforseen seven weeks of repair work, I finally got the truck back with the new tires. So far I'm thrilled with them, I live in the city in an area with a lot of little small streets and they're absolutely destroying the snow banks. I also drive a minimum of 50 highway miles which they've been unbelievably quiet and smooth on, I'm thrilled. Next step, try to find a way to get back at least a little of the mpg's I've lost.

The picture quality is pretty poor, which I apologize for, the conditions haven't been all that great lately.

sab316 · February 2, 2011

Looks good man! Look into getting a tune by Black Bear Performance, I really love my tune!

bluegrassZ71 · February 2, 2011

How many MPG did you lose?

maffbr01 · February 2, 2011

How many MPG did you lose?

I'm trying to work that out now. With the larger wheels I can't imagine that the calculations the truck provides are all that accurate, either on my speedometer or with the MPG's. If I had to guess, I'd say it's seeming thus far to be around 3-4 with a combo of the tires and the leveling, but I could be overshooting it some.

Looks good man! Look into getting a tune by Black Bear Performance, I really love my tune!

Thanks dude. I was researching those on here last night, seem to be a quality investment. If not for anything else then so my speedometer would at least be accurate.

kdixer · February 2, 2011

Considering you have the stock Z71 wheels your truck most likely had 265/65-18's from the factory. The 275/70-18's are .08" taller . therefore just multiply your actual miles traveled per tank by 1.048 and that will give you the corrected miles per tank.Then just calculate you mileage from there. I am curious to see how the tires effected your mileage as I am considering the same size.

maffbr01 · February 2, 2011

Yeah they were the 265s before I put these on, I had been averaging around 20 on the highway and 16 overall, with a lot of city driving, before the install. I filled up yesterday and I've been tracking my mileage thus far. I drive a good amount to and from work every day so I should have an answer for you, and myself, by the end of the week. I'm rather curious as well.

fello026 · February 2, 2011

What is the biggest bfg at ko you can fit on a 09 sierra 1500 z71 4x4 with 18" wheels? No level.

Also... Why is everyone so quick to level their brand new trucks and so comfortable with it when it voids your warranties and it's known they ruin your front end components?

Or are these myths?

700 sportsman · February 2, 2011

Your dealer would have to be extremely picky to void your warranty, in fact I have never ever heard of a warranty being voided due to a leveling kit. The people that have trouble with components are usually running over a 2" kit, or have a lift, bigger tires, or something else adding even more stress.

I'm not saying there haven't been issues with the 2" with stock components, but the mod is definately worth while

maffbr01 · February 3, 2011

What is the biggest bfg at ko you can fit on a 09 sierra 1500 z71 4x4 with 18" wheels? No level.

Also... Why is everyone so quick to level their brand new trucks and so comfortable with it when it voids your warranties and it's known they ruin your front end components?

I have the Z71 wheels, albeit in the Chevy style, and 275 is probably the widest you can go on them, or so I was advised. I'm not sure whether or not they'd rub without a leveling kit, but if I were going to try it I'd probably stick to the 275/65's. But then again, I'm still pretty new at this and get all my information from this forum, so I could be way off.

As for messing with the front end, I bought my truck used, it's nearly four years old overall, so I only have about a year left on the warranty. I'd rather play around with it, make some modifications, and enjoy it the way I want it then worry about what the dealer will say, but that's just kind of how I am. Thus far I have to say that I'm thrilled with how it looks and how it rides, both the tires and the QuickLift, so I'll worry about the rest as it comes.

cparks555 · February 3, 2011

Those Bfg's look really good on your truck, I had them on my '05 and loved them. Should help you out in all that snow!

uh6tdrvr · February 3, 2011

Here is a pic of 305 60's. i dont remember where i found this pic but i have had it for a while.

maffbr01 · February 5, 2011

Considering you have the stock Z71 wheels your truck most likely had 265/65-18's from the factory. The 275/70-18's are .08" taller . therefore just multiply your actual miles traveled per tank by 1.048 and that will give you the corrected miles per tank.Then just calculate you mileage from there. I am curious to see how the tires effected your mileage as I am considering the same size.

According to my calculations I averaged around 14.5 this past week. I had previously been average around 15.9 or so, so it is a step down, but not a huge one. I'm still able to pull in around 19-20 mpg or so while cruising at a reasonable speed on the highway, so I'm relatively happy there. Keep in mind that I live in a city and do a lot of city driving, hence the low overall average. Bottom line is that the truck looks how I want it to, the tires ride great, I'm happy overall, so I'll just have to deal with the loss and find a job closer to home. At least until I can afford a tune.

maffbr01 · February 5, 2011

Those M/Ts look sick Mac. The width fit fine on the stock wheels?

cparks555 · February 6, 2011

I agree, losing a couple mpg's to make your truck look the way you want it to isn't all that bad.

uh6tdrvr · February 6, 2011

Those M/Ts look sick Mac. The width fit fine on the stock wheels?

I dont remember where i got that pick from but i have had it a while. The truck was an 08 new so some time ago. It was picked up from the dealer like that. When he bought it, he handed them the leveling kit and tires to put on and drove it away like that and it didn't rub. I dont remember which forum i got it off of. As fas as it looks, i dont think its too wide for the wheel being that they recommended from BFG is 8.5-11 and our Z wheels are 8 wide. Everyone seems to be fine with 285's on the old 16 wheels and they were recommended for 7.5" - 9" wide wheels. My next will be 305 60's!