Failing to find old post

[Biker]

I've been looking for a old post for about a month about safe tire sizes for an original 70 series axle. I want to say it mentioned 31s being the largest tire to safely run original BJ70 axles without risking damage. If memory serves, it had something to do with temper treatment making the axles last forever at stock loads, but too brittle for oversized tires.

Has anyone got any input?

 

[coldtaco]

Haven’t heard about that. Lots of people been running 33” tires and 35” tires (especially in Australia) without any long term negative effects. Usually any axle problems stem from abuse or improper maintenance

 

[JuanJ]

Hello,

I remember Rosco / @roscoFJ73 once wrote that big tires destroy Land Cruisers. By "big" he meant wide/fat tires.

Then he made the point that skinny tires, also known as pizza cutters, are the way to go.

70 Series' stock gear ratio allows for 33 in. tires, and even 35 in. The latter, however, requires modification, namely moving the front axle 25 mm to 30 mm forward; otherwise they rub.

12.5 in. wide tires rub and make steering harder, Ask me how I know.

10.5 in. wide tires or less are best for 70 Series.

Keep in mind that you have a 3B engine, which is not too powerful. This engine may struggle to move a truck with 33 in. tires.







Juan

 

[roscoFJ73]

I've been looking for a old post for about a month about safe tire sizes for an original 70 series axle. I want to say it mentioned 31s being the largest tire to safely run original BJ70 axles without risking damage. If memory serves, it had something to do with temper treatment making the axles last forever at stock loads, but too brittle for oversized tires.

Has anyone got any input?

32 inches on 16 inch rims are the factory size for a 7* series. They handle a 33inch ok, but as you get bigger it affects the brakes and acceleration.
On the road you could almost run anything, off road, not so much.

 

[Biker]

Hello,

I remember Rosco / @roscoFJ73 once wrote that big tires destroy Land Cruisers. By "big" he meant wide/fat tires.

Then he made the point that skinny tires, also known as pizza cutters, are the way to go.

70 Series' stock gear ratio allows for 33 in. tires, and even 35 in. The latter, however, requires modification, namely moving the front axle 25 mm to 30 mm forward; otherwise they rub.

12.5 in. wide tires rub and make steering harder, Ask me how I know.

10.5 in. wide tires or less are best for 70 Series.

Keep in mind that you have a 3B engine, which is not too powerful. This engine may struggle to move a truck with 33 in. tires.







Juan

I've got a little more than a 3B, 13BT actually, but I understand where you're coming from.

I'll see what my options are locally for new leafs and shocks all the way around and pushing the front axle forward on a new main leaf

 

[Biker]

32 inches on 16 inch rims are the factory size for a 7* series. They handle a 33inch ok, but as you get bigger it affects the brakes and acceleration.
On the road you could almost run anything, off road, not so much.

I was not aware that 32 was the norm. Thanks!

 

[coldtaco]

I ran 255/85/16 on the BJ70/71 I used to have without any issues.

 

[Gun Runner 5]

Ones right foot is probably the culprit more often than tire size.

 

[jblueridge]

Yes. 33’s on mine right now.

 

[roscoFJ73]

I was not aware that 32 was the norm. Thanks!

They were actually 235x85x16 . Some of the BJ71/73/74 had 15 inch rims with high profile tyres . And 80 and 60 series also came with 15 in rims in some markets

 

[aussie75series]

I have been running 32x11.5 on 15" rims for 30 odd yrs. I did try 33x12 but it was too hard on drive line eg having to drop down gears on same hill. 32" is the same as original split rims.
I have put on about 400,000 kms (250,000miles)