Question about 30x9.5 tires

Fitting oversize tires, raising and lowering, suspension modifications...

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Retep
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Question about 30x9.5 tires

Post by Retep »

If I replace my 235/75’s with 30x9.5’s will my truck suffer any loss in performance? I know the 30’s aren’t much bigger diameter and probably not much heavier, however I am concerned about reduced off the line power or unwanted downshifting out of OD and gear hunting at highway speeds. I understand this can be a problem when going to a larger tire.
I do have 3.73 gears, so that will help. I know ZR2’s come with 31’s and they have 3.73 gears.
I would realy like 31x10.5’s but a lift is not in my future. :cry: Should have bought a ZR2.

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Pete
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Re: Question about 30x9.5 tires

Post by Conman »

Retep wrote:If I replace my 235/75’s with 30x9.5’s will my truck suffer any loss in performance? I know the 30’s aren’t much bigger diameter and probably not much heavier, however I am concerned about reduced off the line power or unwanted downshifting out of OD and gear hunting at highway speeds. I understand this can be a problem when going to a larger tire.
I do have 3.73 gears, so that will help. I know ZR2’s come with 31’s and they have 3.73 gears.
I would realy like 31x10.5’s but a lift is not in my future. :cry: Should have bought a ZR2.

Thanks,
Pete
30" tires should not be a problem but from what I see, 30x9.5 will rub without a lift still. My 235x75 rub the flares stock so I can def. see 30x9.5 rubbing on my truck. :(

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Post by 02bluezr2 »

My dad has an 01 cc and he just put some 30's on his truck. As far as I know he has had no probs with them. He only said that there loud. :lol:
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Re: Question about 30x9.5 tires

Post by Retep »

Conman wrote:
30" tires should not be a problem but from what I see, 30x9.5 will rub without a lift still. My 235x75 rub the flares stock so I can def. see 30x9.5 rubbing on my truck. :(

Con
I don't have flares, so I don't think rubbing should be an issue. But I will look a little closer with the wheels at full lock.
02bluezr2 wrote:
My dad has an 01 cc and he just put some 30's on his truck. As far as I know he has had no probs with them. He only said that there loud.



Does your dad have any rubbing with his 30's?

Thanks,
Pete
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Post by AZS10Crew »

30's will more than likely not rub. Mine only did when I had the front swaybar disconnected and flexed the front end a lot...then they rubbed on the top of the wheel well. During normal driving they never rubbed at all.

With 3.73 gears, you should be fine with 30's. I had the smaller tires (235/70's) on mine and 3.42 gears, and I noticed a difference...but you shouldn't with the bigger gears and bigger tires already.
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Post by smokinjoe »

ive got 30' bridgestone duelers wich are a fairly taller tire,they never rub the inside of the frame and only rub anything if im flying down the road and hit a bump, but i put new shocks and it rides much better, 30's are definatly louder than stock,ive got the 3.42 and i havent noticed any difference in power loss or highway speeds or too much shifting.the only left to do is get the speedo reset
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Post by Matt »

I got 30's on my truck and I have no rubbing at all. They are very loud and everyone that drives it and doesnt know that I got them on there complain. They think that it is going to fall apart. Good for me. Keep unwanted drivers out of my truck. I got my on 01 barebones S10 steel rims. http://www.s-10crewcab.com/coppermine/d ... cat=&pos=6 thats a pic of them.
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Re: Question about 30x9.5 tires

Post by 02bluezr2 »

.
02bluezr2 wrote:
My dad has an 01 cc and he just put some 30's on his truck. As far as I know he has had no probs with them. He only said that there loud.



Does your dad have any rubbing with his 30's?

Thanks,
Pete[/quote]

No he dosent. :D
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Post by Retep »

Thanks to all the replies. Sounds like I am a go with some 30" Dueler AT revo's when I scrub off a little more tread on the stock Goodyears.
I am curious why the 30's would be louder. Also, can the dealer recalabrate my speedometer and odometer?

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Pete
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Post by adrenalnjunky »

Good choice on the Revo's.

The 30's will only be louder if you go to a At or MT tread pattern, but since you are going to the revo--it might actually be quieter.

The revo's on my dad's Z71 are quiter than the all-weather tire that was on it before -- buddy of min just replaced the stock Goodyear AT-S on his wrangler and says his are much quieter too.
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Post by AZS10Crew »

Yeah...our tires are only louder because they're knobby tread tires. Gives that nice truck-like hum on the freeway though. :mrgreen:
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Post by adrenalnjunky »

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Post by Dragonmaster »

The dealers usually can only select stock sizes for tires on their scan tools. You would have to go with a 31 the same diameter as a stock bfg or the new generals if you want anything bigger than a 235/75. An HPP3 is your best bet as it will allow you to change for your gear ratio too, and has an added benefit of increasing trans pressures for better gear hold.
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Post by Matt »

as an X dealer mechanic and soon to be a dealer mechanic again soon, I can tell you as a GM certified mechanic that yes they can recalibrate your speedometer/odometer, but would you really want to? If you think about it the same way I do, a bigger tire will rotate less times per mile than a smaller one, 235/75 to a 30X9.50 is not that much of a difference, I think its about a 1/2 inch or so. So therefore you get that much more per mile that does not add up on your odometer. As far as your speedometer being off, its only about 1 or 2 mph. Usually the factory sets them a little slow anyway. My tires are 1mph off from the other ones. A good way to check this out is to wait for the police to put up one of those stupid speed check signs and drive by it a few times so you can see how fast your going. Another thing with the dealer is that not all of them will recalibrate your pcm for you changing your tire size. If they do it will probally cost you a few hundred. Even though it will only take the mechanic 2 minutes to hook it up to the computer, you will probally be charged for atleast 1/2 hour. I think a recalibrate from the dealer takes about 10 minutes. Some times I feel sorry for people that cant fix their own cars, then I get my paycheck and it doesnt bother me anymore. Not that we rip them off, but sometimes it sure seems that way.
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Post by ZoSo »

get a superchip programer
add horses
tire size
shifting pattern
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Post by HenryJ »

Dragonmaster wrote:The dealers usually can only select stock sizes for tires on their scan tools....
While it may be true that they can not select ?any? tire size, they do have a quite broad range to choose from well over 2" + or -.
I just had a 1999 fullsize recalibrated there were options for tire sizes with wheels ranging from 15" through 20". There are way more options than the stock tire size in the door jamb. Don't be afraid to have a dealer recalibrate your speedometer, they can do it.

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