Tire size choice.

[kenm78]

Ok my stock tires size is LT235/75R15 computes to about a 28.87 tire diameter. And at 65 MPH i am around 2300 RPM. If I go up to a 31x10.50R15 that brings my diameter up to right short of 31 inch diameter. I found a RPM calculator online were it asks the for the tire diameter I plugged both sizes in and my factory size was really close to what I see when I drive it. When I plug in the 31 inch tires into it It drops my engine RPM down about 150 RPMs at 65 MPH. Do you think this will increase fuel economy or decrease because of the heavier tire? There is only a $20 difference between the two sizes so I'm down to knit-picking before I purchase either one.

[Restrorob]

On highway cruising I've found in my 97 if I stay around 2200/2300 (65) my mileage is best, Moving up to 2400/2700 increases fuel consumption (higher rev) and slowing down 1800/2100 lowers it due to a slight lug.....

I've tried to follow car club members to shows but they seem to want to cruise a speed that's too slow, This puts a lug on my BB in 5th gear and dropping back to forth puts it in a higher rev. I now just meet them at shows so I can save that little bit of fuel, And around here it's nothing to drive 40 to 75 miles to a show so every little bit helps.

Just for what it's worth.....

[BIG10]

Going to a bigger, heavier tire will decrease fuel mileage slightly, but probably not really noticeable in these trucks. IMO the 31x10.50 would look great on your 4x4. The only issue is maybe throwing off your speedo by 1 or 2 mph. Which ever way you go, show us pics when you get them.

[macdaddydelux]

can i run a 31 on a 2wd??

[BIG10]

Yes, you can run a 31 on 2wd. You might have some slight rubbing issues (not sure), but it will work. I've seen a few and it looks a little funny IMO, but if you like it then that's what matters.

[macdaddydelux]

well i want to put a nice set of wheels & tires on my truck but do NOT want to lower it b/c this truck will still be used to haul firewood, pull atv/boats, etc...since my truck is a 2wd my options are limited, I really wish i could just level it out or do a very small lift to give it a nice level stance & a more aggresive tire

[Restrorob]

Originally Posted by macdaddydelux

I really wish i could just level it out or do a very small lift to give it a nice level stance & a more aggresive tire

So why can't you ? A set of drop shackles dropped the back and leveled my 74 out, That was the first thing I did after buying it....

[macdaddydelux]

yea iv seen them for sale but just havent been able to talk myself into "lowering" it, what size wheels & tires could i run..i was really wanting something like 20s w/33" all terrains but thats not going to happen lol, i do go through some mud & creeks but mainly use it on highway or dirt roads..any pics would greatly help

[macdaddydelux]

If I were to just lower the rear to level it out how would 22s look vs 20s, I would love a more aggresive tire but I also want to have that sport truck look, any pics???

[BIG10]

You could also just lift the front a couple inches if you want to level it out and run a more aggressive tire. You could at least run 31's without rubbing. Scan through the "pics of long beds, pics of short beds" threads. There are lots of great pics and ideas in there.

[BigE77']

Ive run 31's on a couple different square bodies and never had a rubbing issue. They were both 2wd half tons/ one was a heavy half. If that helps at all

[kris's66lwb]

my 80 big 10 ive got the stock 235s up front and in the back im running 31 13.5 tires no rubbs but it raises my 65 and up mph rpms to about 2500+ and i lose economy unless im regeared i have 342s now