I am looking at an '04 Tahoe that had oversized premium 20+ wheels and wide tires on it. Used 2004 Chevrolet Tahoe AUTO For Sale | Beaverton OR

I know nothing about mechanics, but someone told me that this might put extra strain on the drive train, etc. From what I can see, it is common to do this. Am I right, and does it result in normal wear and tear on the vehicle? Or, is it likely to be problematic? I don't think the Tahoe was lifted. It has smaller tires now. (I've only seen pictures from an out-of-state dealership.)

Thanks so much for any help.

CJ

 

the GMT900 can handle 22s without issue, and that's what is factory on the Esky and optional on Tahoe...

I think you could get 20s factory on the GMT800 Denali... so I think you will be fine.

usually huge rims cause a problem for cars because of smaller suspension components or crazy sizes, but 20 isnt all that big when you have a 31-33" tire...

 

A simple answer to your question is you'll be fine. Those rims are not that big for that Tahoe.

 

Greetings MountainLady, welcome to the Forum.

I agree with Sabr's very informative post, but if I may, add a little deatil...

Drive Trains are pretty tough, and to say that increasing a Tire size (over recommended) would put more strain on them is technically true, but rarely more than they can handle.

When setting up any vehicle, the Manufacturer may offer several options on Rim/Tire Size, BUT, the one factor that they will attempt to be consistent with, is the "Diameter of the Tire". So, what they do is vary the Diameter of the Rim AND the Proportion of the Sidewall (that's the 20R through 75R number), to maintain the overall Tire Diameter. The Proportion or Height of the Sidewall to the Tread Width, is also referred to as "Profile".

Keeping this measurement within a given range as Sabr has pointed out, will allow compliance with several systems on a Vehicle. With the onset of Computer Technology on our Vehicles, though not absolutely necessary, it is wise to abide by the recommendations.

Let me give a brief example...
Here are some sizes of tires which are recommended for your vehicle.
265-75R-16 is 31.6" in diameter*.
265-70R-17 is 31.6" in diameter*.
285-50R-20 is 31.3" in diameter*.

Though the 20" is .3" smaller, that is close enough not to majorallly effect the Speedometer Reading, or other calculations the on-board Computer would make with the set reference of 31.6". You can see how the Rim Diameter, Tread Width and Profile, are manipulated to maintain the overall Tire Diameter.

Now, why would/do they have variations in this ?

Well HA, there used to be some very solid reasons for this, but, now a days I think it's more an issue of how "COOL" it looks

Anyway, if they were trying to make a Family/Luxury model, they would choose a tall Profile like a 75R. That puts more distance and cushion between the Rim and the Road, allowing for a softer ride.

IF they were attempting to create a Sports Feel to the vehicle, they would reduce the Profile like to a 50R or less, to take the sway out of the Sidewall, and increase the "control" the the driver feels/has from that.

Now, there's one other important issue, when you're replacing the tires on a given Rim. Hopefully, the person who bought the Rims, did so with good information about the requirements of the Vehicle.

Let's say you have 20" Rims, and they are 9" wide.
It's important to keep the Width of the Tire Tread, the same as the Width as the Rim. Keeping the Sidewalls of the Tires straight up and down, makes for the best Performance, Control and Tread Wear.

So, in this case, you would select the Tread Width according to the Rim Width, the Mounting Size according to the Rim Diameter, and then allow the Proportion of the Sidewall to "float", to achieve the overall recommended Diameter of the Tire.

Hope this helps,
Have a good Day !
S.W.

* = There may be some slight difference in dimensions, between different Manufacturers Tires.

 

More rubber on the road can improve handling but the extra friction also reduces mpg a little bit....

 

in2pro,

You're quite right, which gives one a great incentive to maintain proper inflation pressure.

I wish I was a better mathematician, and could create a formula for the trade off point, where the weight of the vehicle and how much rubber you had on the road, started detracting from wet traction..ie..floatation. Might save a life or two.

Makes one think that Tread Design is more of an art than we thought !

 

the 'reason' for minimizing the sidewall size (bigger rim) is to reduce the amount of flex between the tire and the wheel... thus giving you more control and feeling inside the car. (flex, left and right, ie: hard cornering)

the down side is 1. cost 2, the wheel weighs more than rubber (hence driveline wear), and 3. the ride... reducing sidewall means less rubber to absorb the impact of pot holes at 65 MPH...

the new 'reason' for big wheels is... mostly looks. but it started with racing / performance.

even the esky came with 18s to increase ride comfort... more rubber = more cushy... less rubber = less flex and more stability / less roll (tire wise, not body roll)..

anyway; the truck will be fine.

 

Nice little lesson about rims and tires--thanks very much to each of you!

 

Another consideration about the bigger wheel/tire being heavier is the brakes. So if the truck is OK from the factory w/ 20s, then the brakes should be OK. But when someone goes to 22s or 24s, then a brake upgrade should be considered.

 

Back in "the day", when most American products didn't have Disk or Power Brakes, putting larger tires on a vehicle then was relatively popular. I have on several occasions, went to the Junk Yard, and stripped the Slave Cylinders off of a Cadillac, and put them on smaller/lighter GM vehicles.

For instance the original sizes were...
Fr: 1", Re: 7/8"
then the replacements were...
Fr: 1 1/8", Re: 1"

A respectable increase if the breaking power with the same Master Cylinder, with minimal additional travel of the Pedal.
Additionally, I really liked the Anchor Pin Centering Eccentric adjustment on older GM's, one could really create a high hard Pedal ! !