Stock CC- what size tire

[Ar15 guy]

I recently bought a 01 CC and I'm looking to get some tires for it. I'm pretty set on a Yokohama geolander ATS. The stock tire size is a 235/70/15, but I was wondering how a 235/75 would look. I also have a set of 16" 95 TA 5 spoke wheels I could stick on it. I would run a 235/70/16. I may crank to torsion bars a little to help level it out.

Should I stay stock or upsize to a 235/75/15 or go 16"? How does it look with the ~1" increase in overall diameter.

[roadrunner]

My 01 came with 235x75x15 tires as stock so I would see no problem with them on your rig. Only thing I ever noticed is on extreme articulation with aggressive square lugged tires the inner fender lip will catch on the lugs during bottom-out situations. I have cranked my T-bars slightly to mainly level the truck stance which helped a bit. Did this to correct a lop-sided look in the back caused by the right front being adjusted too low. I presume you are referring to the 16" tires with the 1" diameter increase? You would have to crank the bars a bit to get clearance for anything larger than the 235x75x15 tires especially if they have aggressive lugs on the sidewalls. I am running BFG AT KO tires. Welcome to the forum!

[Ar15 guy]

A 235/70/15 is 28'' tall, a 235/75/15 is 28.9'' and the 16'' is 29''. So either upsize from stock will be close to 1'' difference. The Yokohama ATS is not as aggressive around the sidewall as the BFG AT KO.

[zjrebel]

You will be fine running 235/75/15's. You may even be able to run 30/9.5/15 with a small torsion crank which you want to do anyway.

[killian96ss]

Anything bigger than a 30" tire will require modifications to fit, especially if the tire has an aggressive tread pattern that extends to the sidewall. If you want to run the Geolanders AT's I would stick with the factory rims. If you like the TA rims I would go for more of a street tire. You could obviously do both either way, I just personally think it looks funny having off road tires on street rims. There have been a couple of CC owners who had Camaro or Firebird rims that did look nice, but they were mostly street driven also. I think the street rims look best on lowered S10's. I've always thought a lowered CC with an AWD conversion and Corvette rims would be cool!

Steve

[urimashe]

i beleave if you do a quick forum search here there is a topic on how chevy actualy started recomending bumping the tire size from 235/70 to 235/75

[HenryJ]

Not exactly a Chevy recommendation. The 235/75-15 was the optional tire size offered as an offroad package along with the lower 3.73 gear ratio and the locking rear differential.

[Ar15 guy]

I went ahead and ordered a set of 235/75/15 yoko geolander ATS. I'm going to raise the torsion bars a smidge.

Is the ZR5 actually raised up any higher than a standard crew cab? I know I have the optional 3.73s and locker in mine.

[_STUCKY]

By "locker", you mean the "gov-bomb", right? That's not a real locker...

[Ar15 guy]

I guess. I'm a f-body guy...this is my first truck.

[HenryJ]

By "locker", you mean the "gov-bomb", right? That's not a real locker...

Actually it is a "true locker". It is not a limited slip or spooled carrier and does positively lock both axles. Yes, the Eaton (RPO G80) GovLoc locking differential.
By your comment, I assume you are not a fan? Treated properly and well maintained they are one of the better lockers for street use. JMO.

[roadrunner]

Not to upset folks here but my truck came stock with 235x75x15 tires and is NOT part of an off road package. In addition it has 3.54 gearing also stock. I am the 2nd owner and was given the original window stickers by the first owner whom I am acquainted with. I have also read and decoded the rpo codes from the glove box and they confirm the stats I've just given. Perhaps it's something to do with production dates or other criteria but this is the way my truck was produced.

[HenryJ]

Sumth'n funny right there. 3.54 was not offered as an available ratio. What RPO code do you have for the gear ratio?

GU2 2:73 ratio
GU4 3: 08 ratio
GU5 3:23 ratio
GU6 3:42 ratio
GT4 3:73 ratio
GT5 4:10 ratio
GQ1 Open Differential Rear Axle
G80 Positraction/Locking Rear Axle

GU6 and GT4 came in the crew cab trucks.

The 235/75-15 is listed as the "optional off road tire" size. RPO QEB= Tire all, P235/75R15/N WOL R/PE ST TL OOR (OOR = Option Off Road)
Yours could have been ordered with that tire RPO.

The G80 GT4 and QEB were offered as part of a drivers convenience sales package.

[killian96ss]

GM never offered a 3.54 rear end ratio in any of there vehicles. The old 12 bolt rear ends had a 3.55 option, but not the S10's. You are probably thinking 3.42 ratio.

Steve

[_STUCKY]

When I hear the word "locker", I picture a positively locked differential. Anything from a Detroit to a spool to a welded set of spider gears. Those would have no "differentiation" (is that a word lol). Those would bark the tires on pavement while turning. Those would help propell you forward though a mud hole or up a pile of rocks. Those would not let the tires/axle shafts change speeds from each other.

When I hear the words "selectable locker", I picture an ARB or an Auburn ECTED or an OX locker. All of those can be in an "open" position and function as an open differential, then when you push the button or pull the cable, BAM full locker, full power both axle shafts.

Now when I hear about the gov-lock, since it has clutches, since it lets the tires spin at different speeds, since you have to have wheel speed up to make it work (at least a worn out one), and especially since I've been stuck with a non functioning one more times than i would like to try to remember, I do not consider it a true locker. They are prone to failure when abused. Now for a street driven truck, it's just fine, but street driven trucks do not need lockers.

I found this: http://www.youtube.com/watch?v=6Zit49L-7_A

Maybe it's the push button lockers in a couple of our tractors or the off roading background I have or all the time spent on pirate.

Also when I bought my 91 k5, it had one in the back, not stock I'm pretty sure. It exploded on pavement and left me stranded. I was not abusing it at the time and the truck had 31x10.5s on it. Only thing salvageable from it was the pinion, the rest turned into shrapnel. I was not pleased.

[roadrunner]

I stand corrected HJ. I Was having a brain fart on the ratio. It is 3.42 (GU6) and further check of the rpo codes revealed, even though the paperwork doesn't indicate it, it was indeed ordered with QEB tire option. Perhaps a dealer selection??? as the previous owner indicated he did not order with any special off road packages. Whatever the case I have been happy and well satisfied with both the tire size and ratio for my usage.

[HenryJ]

Actually it is probably a much better final ratio. Mine got its best mileage after jumping up to 33" tires running the 3.73 ratio.

There really were no special offroad packages for these trucks. Some options required others though. Cheaper to get the G80 GT4 and QEB , than to try to get just the G80? I thought it was sort of funny my window sticker listed the tires as "off road" they really didn't look too aggressive to me:

[Ar15 guy]

If I wanted to go to a 3:42 rear end gear I assume there is something I would need to change the front gear ratio of the front axle?

I ask this because I do daily drive this truck and any extra gas mileage would be nice.

My truck has high mileage, but the body is mint. A friend of mine has a reconstructed 99-00 Sonoma x-cab 4wd that has sat for several years. The fuel pump went out years ago and we changed it. He never even drove it and somehow convinced himself the intake manifold was cracked. He tore halfway into it and never did anything with it. The entire drivetrain has less than 80k miles on it. I could probably get it dirt cheap. Wonder if the motor and everything is swappable?

[HenryJ]

The efforts would not yield enough difference to justify the effort. Run the 235/75-15 and keep and eye on the air pressure. Light right foot and that will be as good as it gets.
These trucks are not known for great mileage.

[Ar15 guy]

Once my fiancé finishes her student teaching I'll finally get my accord back. After that gas mileage won't be an issue. Right now she is driving 100+ miles a day so she is using my beater.

[Ar15 guy]

I have considered throwing a set of headers on it and getting rid of the cats. May help mpg and power a little.

[HenryJ]

Ditching the precat is not a bad idea. The system really is not restrictive. Again I don't think modifications will pay for themselves. If you need better mileage, invest in a different vehicle.

[Ar15 guy]

I already have a second car, but on most vehicles I have owned I have gotten a nice power boost from headers and cat delete.

[HenryJ]

Replacing the stock muffler and perhaps the pipe from the cat back can be a performance increase. Don't do it expecting noticeable mileage gains though. It actually does quite the reverse until you let up on listening to it and ease up on the skinny pedal.

Today's exhaust manifolds are really pretty good. In many cases better than headers. Unless you are building a hotrod and have done lots of internal modifications, I don't think I'd bother in this case.

[killian96ss]

Some of the factory GM hydroformed exhaust manifolds (LS7 for example) are almost as good as headers, however the factory cast iron 4.3L exhaust manifolds are not all that great. Gibson and JBA are good headers for the 4.3L engine. The hp and tq gain will not be as much as a V8, but you should still see at least 10-15 hp.

Steve

[Jongo88]

Here is a crew with TA wheels and is lifted with 265 70 16's..