Tire Talk

[Uglydog56]

The rear tires on my Crown are Bandag recaps, 11R 24.5.  The tread looks like a set of mudders for my wife's jeep.  I can maneuver it around in the muddy vacant lot next to my house, while my dually pickup spins and gets stuck.  I think that is to which TomC refers.

[TomC]

Like Rick said, some of us are more adventureous then others. If you go into mud and soft sand, a traction drive tire will many times get you out. But-my point with a 4 spd manual, the 1st gear is so high, mud and sand will just let the tire settle in and won't have enough power to pull it back out of the trench-hence a traction tire would be useless.
I run only all position tires on front and back of my bus since I will never get off road and will never be in snow (living in L.A., I can do that).  Good Luck, TomC

[RJ]

Thanks, Tom. . . Now I get your point.

Understand about the geared-high 1st (and reverse, for that matter).  But then again, the OEM gearboxes were never designed for the type of operation we busnuts put them to.

FWIW & HTH. . .

[luvrbus]

Why would one give up a +or- 1inch of width to go from a 12r22.5 to a 11rx22.5 you tire experts enlighten me or humor me tire manufactures have said for years the wider the tire the less rolling resistance is that BS  or what ? 

As a Eagle owner for years I can tell you a Eagle with 12rx22.5 tires drives and handles a lot better than one with 11x24.5 plus they have 4000 lbs more GVW and the wider 315's 22.5 are even better IMO

[RJ]

Why would one give up a +or- 1inch of width to go from a 12r22.5 to a 11r22.5?

Clifford -

Simple answer?  $$

The 11s are cheaper than the 12s.

FWIW & HTH. . .

[TomC]

Less rubber on the ground and the higher air pressures, the less rolling resistance. Also the less amount of tires means less rolling resistance-this is why 18 wheel trucks are going to super singles so to only have 10 tires flexing.

As to the difference between 12's and 11's-if your bus weighs within the limits of an 11-why pay for a 12? And as stated, usually only buses use 12's and most everything on the road uses either an 11 or the lower profile metric version of an 11. Trucks and buses are now switching to the metric version of the 12 which is the 315/80R-22.5-which is a big chunk of money more then a 11.  Good Luck, TomC

[luvrbus]

Yep and trucks have a lot more caster built in than a bus if I remember right a Eagle was 3 degrees tops maybe 3.5 

[TomC]

When I found out how close in ratings the 11R-24.5 16ply is compared to the 12R-22.5 16ply, this is why I changed my bus from the 12's to the 11R-24.5.
12R-22.5- 7390lbs per single tire; 6780lbs per tire on a dual
11R-24.5- 7160lbs per single tire; 6610lbs per tire on a dual.

And on my bus, even though I have a 13,000lbs front and 23,000lbs rear, I only carry 10,500lbs on the front and 20,500lbs on the rear-hence even with the 11R-24.5 16ply tires that can take 120psi, I only run 90psi. My ride is very good with the tire pressure and the tires don't run hot.

Caster is a function of factory requirements to overpower the power steering. Good Luck, TomC

[rusty]

another function of caster is to keep the vehicle going straight. Non power steering vehicles had very little caster as it is harder to turn a vehicle with more caster. The vehicle with caster will lift as it turns. 
Clifford If you find an Eagle with that much caster in it it will be rare. 2-2 1/2 is all you ever see. That front end was started long before power steering was used much. The design has never changed. That is why it is very important to keep things tight in an eagle front end.

Wayne

[luvrbus]

I knew it wasn't much Wayne the buses like the Eagle even the Prevost with the IFS are limited on the caster they are nothing like a straight front axle bus or truck the narrow tire just don't work on the front IMO

[John316]

FWIW, we run 315's on our steer and 12R's all the other positions. We need every bit of the 315's on the front. We are 45K with a medium load.

We can get stuck on a banana peal (my guess is that goes for most). We haven't spent the money on the open shoulder tires, because if it get's at all soft we seem to just sink. That is one of the reasons we carry tire chains with us year round. Been times when grass has just been steep and slippery that we have needed chains. Otherwise it is pavement for us (except that isn't always fool proof...LOL)

John