Hummer Wheels & Toyo Tires

[davzog]

I just purchased a set of four Hummer H2 wheels...they are 17 x 8.5 and look great IMO.

 

The bolt pattern is exactly the same as the HD2500, so that works ok.

 

Of course, I need to go from a 245x75x16 to a 265x70x17 since the wheels are larger. I have decided on Toyo LT Open Country A/Ts, I think.

 

My concern is that the new tire is 4% taller than the old one....this will certainly affect my speedometer (not too much), the antilock brake system, and the final drive ratio.

 

I think I can get the dealer to set up the computer for the speedometer and that should fix any issue with the antilock brakes....

 

My biggest concern is the final drive ratio....with the 6.0 and 4.10 gears I am at about the limit to pull my 5th wheel...is a 4% change going to have a BIG effect on towing?

 

Has anyone done this???

 

Thanks in advance for any help...

 

Dave

[Haulin' 8.1]

I don't think you'll notice it. With 4.10's it still won't be as much as the stock tires with a 3.73.

 

Vernon

[davzog]

I believe that is correct....since there is about 4% difference in tire diamater difference, I multiplied 4.10 by 96% and got 3.936....

 

I hope I don't see too many towing issues with the 3.94 ratio...thanks

[sgilly8]

I don't have those exact rims and tire but I did just recently install a set of aluminum OEM rims with 265/70R17 Bridgestone Duravis tires that came off of a NBS truck. I have not noticed any difference in pulling power but my travel trailer is only about 6800LBS fully loaded. I also have the 6.0L with 4:10 gears. I have noticed that I lost on average 1mpg ( hand calculated every fill-up ) but the truck looks a lot better with the bigger tires. I did not realize it would affect my braking so I'm definitely going to get the dealer to set up the computer.

 

Hope this helps,

Scott

[davzog]

Thanks for the reply, Scott...

 

I am sure not an expert, but my understanding is that the larger diameter tires might be an issue for the antilock brake system, and should not affect regular braking.

 

In terms of mpg calculations, someone pointed out that if I hand calculate my mpg (miles driven / gallons) I have to multiply that by 1.04 to compensate for the 4% increase in distance actually traveled. He said that when he did this his mpg actually went up about .5 mpg. He did a similar change on his Ford....I guess we'll see...thanks for the reply