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Suburban Tire Size Change... thoughts invited from fellow diesel heads!

K

knkreb

The Bus Driver is here!
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Needin' some new tread on the suburban.... have the stock LT245... thinking of stepping up to LT265... in attempt of getting better MPG without a rear gearing change.

Can you go more/less... pitfalls and good points... thoughts?
 
FWIW after consulting Mr. Bill in Ellensburg I went with his recommendation BF Goodrich Commercial TA in 235, I have better mpg with it's road tread & lower weight than the 265 ATs I was running, I rotated them 1st time @ 40k and the were still like new on the tread, Dennis aka Slim Shady saw mine after 25K last summer rode on them and decided he needed a set as well you could PM him but last time I talked to him he was impressed with his set as much as I am with mine tomorrow in the daylight I'll shoot a pic of the treads, I think I'm around 50K on them now.
 
Is the 235 a little skinnier? I really am hating the E Rated tread I was upsold into. I don't tow nearly enough to justify the harsh ride and weight penalty.
 
Veg_Out said:
Is the 235 a little skinnier? I really am hating the E Rated tread I was upsold into. I don't tow nearly enough to justify the harsh ride and weight penalty.
Click to expand...

yes. first number is the width, second the height ( I believe proper term is section height) as width increases, height does to a point, such as 265/75 will be taller than 245/75, but to really gain in height you need to bump up to another section height class. biggest in light truck is 85. 80 only exists in specialty trailer tires, IIRC (ST235/80R16 is the common)
 
My burb had 235/85's when I bought it, I've been running 265/75 for over 40,000 miles now. Mileage was better with the 235 mild tread tires over the 265 A/T's, the skinny 235's are much lighter. I'm ready for a new set shortly and have to make the decision again on what to go with, I love the look of the 265's so will likely go with them again.

You'll like the added height, lower rpm of the larger diameter tires, but not so sure you'll see an mpg improvement with the 235's over the stock tires.
 
I had 265's on my old 2 door Tahoe. I like dthem and had no clearance issues. I plan I putting them on my new burb as soon as it needs tires.
 
Funnily enough I was just looking at this myself. I am currently on LT265's installed by PO and its time for a freshen up. I was seriously thinking of going back to LT245's because with the 3.42 and some weight on the back she's a wee bit doggy but I like the height of a 265. However I am pondering the 235 with the reduced weight and less width over a 265 just wondering if that will have any marked effect on roll resistance etc.

I can totally see how a 265/235 height on a 3.73 would be a nice combination.

Cheers
Nobby
 
I really like the 235/85 tires on my 3500 with 4.10 gears, it dropped my 65 mph speed from 2500 rpm to about 2250 rpm. Old tires were 225/85.
 
Adding to the above:
Wider tires give you better traction dry. Specifically when you push the limits of acceleration; stopping, turning, speeding up... There is a limit to what the rubber patch can do before it slips under any weight. A bigger patch under the same weight gives you better traction.

Wet wider can be a boat effect.

GM puts as narrow a tire on as they can - for MPG. Less weight and less rolling resistance rubber helps MPG.

I have seen MPG penalties for wider tires on my rides. This is a trade off I am willing to take for better handling and performance. Trailer stability also comes into play for me.
 
Do the VSSB mod and let us know if that makes a difference with your gear ratio and tire height. Inquiring minds want to know.

nobby said:
Funnily enough I was just looking at this myself. I am currently on LT265's installed by PO and its time for a freshen up. I was seriously thinking of going back to LT245's because with the 3.42 and some weight on the back she's a wee bit doggy but I like the height of a 265. However I am pondering the 235 with the reduced weight and less width over a 265 just wondering if that will have any marked effect on roll resistance etc.

I can totally see how a 265/235 height on a 3.73 would be a nice combination.

Cheers
Nobby
Click to expand...
 
235/85 Es on mine let some air out for softer ride, I only press mine up to full psi when towing heavy not much ride difference when I press up to full psi though

No pics camera battery is dead
 
Last edited:
jrsavoie said:
Do the VSSB mod and let us know if that makes a difference with your gear ratio and tire height. Inquiring minds want to know.
Click to expand...

Odd thing my speedo is off by 7 mph higher than gps, yet speed in PCM as seen with scan tool is spot on match with GPS and with those radar speed warning signs same as it was when I had the 265-75s it came with from factory, my height is a littler lower factory 1870# rated rims were 7" wide and now I have Classic MT 8" 3300# rated rims. But speedo with the MT rims 265 vs 235 off just the same as with the factory rims. Bill says some tucks the speedo needle was installed off just a little on the pin I could take it off and try to make it better, but it could also be worse.
 
VSSB mod.

Did I miss something here does an incorrect VSSB have that deeper effect on operation. I never really bothered with it because I always just mentally adjusted gauge readings according to having a taller tyre on the vehicle.

So other than possibly ABS which I never really got to the bottom off as to whether it is based on VSSB - what else does the VSSB have a noticeble effect on? My thought was and is whatever the VSSB is at with my setup she'll be doggy with the extra tyre/ a load and a 3.42 rear.

Of course a chip would be a good thing for this and planned, just never seem to find a spare $500 lying around. :rolleyes5:

Cheers
Nobby
 
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