Tire Advice

[coxfmly]

Hello,
I currently have "stock" sized tires (LT235/85R16) on my 84 Suburban.The truck has the 6.2 / Banks set up with a turbo 400 trans.
I have 4:11 gears in the rear for towing.

I have a friend with a set of Pirelli Scorpion STR tire, size LT265/75R16. He is willing to sell them to me for $80 dollars. What would this size tire do for driving habits of my truck. Will they fit without rubbing?
I am paying $2.80 gal for Diesel and it is killing me.

Would the tires help my cruising on the freeway?
I usually top out at 65 mph to the frustration of everyone in the car pool lane, oh well.

Also, I tow a trailer and with the other tires I can climb any hill @53 mph (2nd gear).
Will I be able to step up the speed a little in 2nd or will this cause me to loose speed.

I am loking into a gear vendor unit but until I come up with the $$ I have to go low budget.

Thanks Paul

[K10ANDY]

they will probly help a bit on the freeway and hurt on the hills and will probly have minor rubbing.

[Ratau]

coxfmly

If one works the tire size back to inches your 325/85R16 come to 31.73

[Craig M]

My dually has the 4.11 gears, TH400 and 235-85R16 tires, same set up as your Suburban. I do not like to go 65 in 3rd gear either, engine is really winding up. I flip on the gear vendors and rpm goes down nicely. For climbing hills with a loaded trailer the 1 st over is also used sometimes. I bought the truck used so did not take the big hit for a new gear vendor unit. Used units are sometimes available in the $1000 range.

[arveetek]

As Danie stated above, the 265/75R16 tires have nearly the same diameter as the 235/85R16 tires you currently have. The 265's are basically the same height, just wider. You probably will not notice any difference at all in cruise RPM's or fuel mileage. If anything, you might lose a tiny bit of fuel mileage due to the wider, heavier tires.

I have 265/75R16 BF Goodrich tires on my pickup, and they fit just fine, nowhere near to rubbing on anything. I went from 245/75R16 tires to the 265, and I did notice a drop in cruise RPM's. But 235/85 tires would be the same diameter.

Going to an overdrive tranny would be the best solution, whether replacing with a 700R4, or adding an aux. unit like GearVendors or US Gear. You could also swap axle ratios, but then you'd lose pulling power.

I absolutely love my 700 tranny, 4.10 gears, and 31" tires. Great combonation for highway driving, towing large loads, and getting decent mileage. I was averaging 18 mpg before my engine rebuild. We'll see what happens after the low-compression, high-flow fuel pump mods get installed.

Casey

[K10ANDY]

the 235s are 29.9 and the 265s are 31.6 . ---metric tire calculator

http://intercotire.com/html/metric-tire.htm

[coxfmly]

Thanks for all of the information.
I think you helped me make my decision and look for a gear vendor unit....thanks again

[Ratau]

6-2 CHUCKVEE

You must have punched in the wrong sizes to get to 29.9

[K10ANDY]

nope . go try it on the link i posted . :D

[arveetek]

6-2 CHUCKVEE,

Sorry, I just used your link and I came up with a tire diameter of 31.7" for the 235/85R16 tire and 31.6" for the 265/75R16. That means the 265/75 is just a hair SMALLER than the 235/85.

I think you must have punched in 235/75R16...that comes up at 29.9".

Casey

[K10ANDY]

yeah i did im an idiot . :rolleyes:

[nape]

My 83 Sub had 235s and I changed to 265s, I noticed a little difference in fuel mileage but no problem mounting on stock wheels or with them rubbing. The best and cheapest thing for mileage would be a good 700r4. I get 20mpg consistently and used to get a little more with the smaller tires. Performance is much better with the lower 1st gear and the overdrive. A good trans and refitting the front shaft is much cheaper than the gearvendor unit. Nape