7.50 R16 Tires and PSI for city driving?

[archaeology_student]

Howdy,

I was curious about tire PSI for the city for a series III SWB. What are most of you running your tire PSI at for city driving with the 7.50 R16 tires? I just don't want to overinflate or be underinflated.

Cheers

[KevinNY]

Bias Ply or Radials?

[archaeology_student]

Michelin XZL radials that are tubeless.

[KevinNY]

The owners manual says 25lbs. front and rear for loads under 550 lbs and 25 front 30 rear for loads over 550lbs.

[pickuprover]

But it also depends on the tire, my last set were supposed to be run at around 55 psi, the new set 35 psi. Ask your tire guru at the local shop, depends on sidewalls and such. I am not sure with those... but I guess, you can never go wrong with the manual.....

[KevinNY]

Most tires of the common 235/85-16 variety were made for work trucks and are E load rated. At 25 psi they are perfect according to my chalk test on the tread. Very stiff sidewalls for a radial.

[pickuprover]

Kevin. I have never truely understood the tire sizing, let alone the pressures... I just make sure that when ever I get a new set of tires (always use the same shop, and trust them....) I get them to tell me the pressure that specific tire should be driven on... they have never let me down on the tire, and so far the pressure...

[KevinNY]

A lot of shop monkeys really don't know much though, careful. They will quote the Max. Pressure that is printed on the side of the tire.

[pickuprover]

Oh I never trust a shop monkey, not even to put the tires on the truck. I am lucky to have a great relationship with my tire shop (well they started out as a tire shop and now are full service...) and always get the same gentleman working on my truck (is old enough to remember when cars had no computer..) and even the owner works on it. Luckily, they have forgotten more about tires than most shops have ever learned (been in business over 50 years.... just about time the old guy retired...)

[300bhp/ton]

Originally Posted by pickuprover

But it also depends on the tire, my last set were supposed to be run at around 55 psi, the new set 35 psi. Ask your tire guru at the local shop, depends on sidewalls and such. I am not sure with those... but I guess, you can never go wrong with the manual.....

Gee 55psi, what tyres where those sounds awfully high.

Anywhere from 25-32psi should work on almost any tyre you are likely to run. For high speeds and heavy loads go with a higher psi.

[TerryS]

Originally Posted by KevinNY

At 25 psi they are perfect according to my chalk test on the tread.

It's good to see that some people still use the tried and tested methods!

The chalk test method is the best way to determine when you're overinflated or underinflated, but is only a good test for pavement use. Take a bigassed hunk of builders chalk and wipe several wide bands across the tread, maybe at three spots, 120 degrees apart. If the chalk disappears in the center, you're running pressures a bit high, if it disappears at the outside edges, you're underinflated.

I run 235/85s on my 110 at about 26 front 30 rear, but go up abit for long hauls on the highway.

A 235 is a big tire for an 88 with a stock engine, so you might want to run a few pounds higher to decrease the rolling resistance.

[KevinNY]

A 235/85 is almost the same as 7.50-16 right?

THIS is a big tire for an 88

[300bhp/ton]

Originally Posted by KevinNY

A 235/85 is almost the same as 7.50-16 right?

THIS is a big tire for an 88

Nope.

235 = width in mm
85 = 85% of the width to give the side wall height
This is missing the rim size.

A 7.50-16 is not a complete size either.
7.50 would be the width 7.5"
16 would be the rim

25.4mm = 1"

So a 7.50 would equal an equiverlent 190 width metric size.

[TerryS]

Originally Posted by KevinNY

A 235/85 is almost the same as 7.50-16 right?

One in the same

[jimfoo]

Originally Posted by 300bhp/ton

Nope.

235 = width in mm
85 = 85% of the width to give the side wall height
This is missing the rim size.

A 7.50-16 is not a complete size either.
7.50 would be the width 7.5"
16 would be the rim

25.4mm = 1"

So a 7.50 would equal an equiverlent 190 width metric size.

Um, I think both of you missed the point. "This" was referring to the 88"
in the picture and the tires on it , I believe.