I've been considering the same question. 265/75-16 tires have a slightly
larger outside diameter than 265/70-16 tires, so you'd feel the loss of a
small amount of power. Gas mileage might improve unless the higher
"effective" gear ratio causes your transmission torque converter to unlock
more often. 245/75-16 tires are about the same outside diameter as
265/70-16, but many folks don't like the skinny look.
I think I'll get P265/70-16 tires. That was Toyota's choice, and they
likely know something I don't about tires for their trucks--although I
disagree with them about inflation pressure, and we all know how they went
cheap with the OEM Dunlops and Bridgestones.
For slippery road traction, I like to have my tires siped when they're about
half worn. I buy new tires with good factory siping. When there's about
7/32'nds of an inch of tread remaining, I have the tire shop use their 5/32"
sipe cutter. By then, the rubber is hardened from many miles of hot road
surfaces & friction, the edges of the tread blocks are worn rounded, and
often the factory siping is worn away.
Ken
> I've been considering the same question. 265/75-16 tires have a slightly
> larger outside diameter than 265/70-16 tires, so you'd feel the loss of a
> small amount of power.
Yeah, I thought about that, too, but I think on a (mostly) unloaded V8 you
would barely notice it, if at all.
> Gas mileage might improve unless the higher
> "effective" gear ratio causes your transmission torque converter to unlock
> more often.
You mean sooner-than-usual downshift? (What does "torque converter
unlocking" mean?)
I haven't even thought about that. You think on a 3% larger tire (which
265/75 is to 70) that would be significant? (How many MPG might I lose on
average on a level road?)
> I think I'll get P265/70-16 tires. That was Toyota's choice, and they
> likely know something I don't about tires for their trucks--although I
> disagree with them about inflation pressure, and we all know how they went
> cheap with the OEM Dunlops and Bridgestones.
I would go with 265/75-s. They are a little beefier and some $20 cheaper as
well (larger but cheaper, go figure), but COSTCO (which is the cheapest
source I was able to find) won't install them, 'cause they are over the OEM
specs. So, I am scratching my head, should I buy them and install at another
place thereby waiving the road hazard, or get the more-expensive (and
less-desired) 265/70s?
> For slippery road traction, I like to have my tires siped when they're about
> half worn.
That's interesting! Never heard of anyone doing that. How much such a
service costs? I hope it's not too expensive.
Thanks, Ken!
dave - 02 Oct 2004 05:18 GMT
> You mean sooner-than-usual downshift? (What does "torque converter
> unlocking" mean?)
The torque converter on almost all newer vehicles locks the two halves at
highway speeds to increase gas mileage. Its acts the same as a manual
transmission when the clutch is fully engaged so there is no slip between
them, the slip in an auto transmission being the fluid.
You can accelerate with it locked, very gently on a flat road. Too much gas
will make it unlock, which feels like a light downshift.
> I haven't even thought about that. You think on a 3% larger tire (which
> 265/75 is to 70) that would be significant? (How many MPG might I lose on
> average on a level road?)
You should actually get slightly better mileage with the larger tire because
the wheels are now turning less revolutions per mile at the same speed. If
the tires are somewhat heavier than the stock tires, this usually balances
it out. Remember to add 3% to your mileage when figuring MPG. 300 miles is
actually 309.
> I would go with 265/75-s. They are a little beefier and some $20 cheaper
> as
[quoted text clipped - 5 lines]
> place thereby waiving the road hazard, or get the more-expensive (and
> less-desired) 265/70s?
265/75 are cheaper simply because they are a much more popular size. Many
full size trucks and SUV's come with this size stock. If you have a Discount
Tire store near you, go to them and tell them what quotes you have recieved
from other stores. They will price match to get your business. The store I
got mine at even installed them for $1 per wheel less their own wholesale
direct price from the internet, after you figured in mounting and balancing,
which is usually $1/inch. A 16" wheel tire is $16 to have mounted/balanced.
J.Smith - 03 Oct 2004 00:00 GMT
Thanks, Dave, for explaining the converter locking (and other stuff)!
> If you have a Discount
> Tire store near you, go to them and tell them what quotes you have recieved
> from other stores. They will price match to get your business. The store I
> got mine at even installed them for $1 per wheel less their own wholesale
> direct price from the internet, after you figured in mounting and balancing,
> which is usually $1/inch. A 16" wheel tire is $16 to have mounted/balanced.
I certainly have a Discount Tire closeby (It's called America's Tire here)
and they do price matching -- only problem, not on Bridgestones, which is a
special order item. (Damn!)