WOW, where did all that crap yesterday crawl out of! Hey, I’m sorry bout not saying anything much GMC, it was as I see it a visible crack in the way us consumers were programmed to see a great buy. It seems to be leaning way off of quality and service and after seeing so many industries implode in the name of price… you guys just can’t let it happen to our awesome vintage RV industry which BTW I see the GMC motorhome at the top of the mountain. But even those at the top will feel the breakdown and guys shoot me if you don’t like what I said.
But be that as it may be, lets forget at least for a bit all of the “beat the price crap and lets talk about our motorhome…..
Before I blow a little thundercarb about tire truing and how it relates specifically to our GMC, I just wanted to show you what I would say is a very together look. This is MoHo fitted with a set of our new design bumpers….. guys, look at this
Just before leaving last nith just before shutting off all the lights I turned around and this view just hit me. MAN, that’s a together look! It’s not a Barris Bat Mobile creation… it’s not an original look do-over no, that is a look I think GM would approve of. The theme of MoHo is a true restomod original look and color wrapped in an all fresh wrapper. My eyes have always felt good about the original silver/black headlight bezels and grill….”OEM” but it needed something to bring the years off the look. This color keyed bumper shape really does it for me. Yes, they are expensive but isn’t anything that’s truly nice….
OK, on to the main event…… So what the heck it tire truing anyway??? And why do I need it???? So, I’m glad you asked…. Oh No, you’ve heard this one from me… it means you’d better strap in, this could get messy…. and long… hey but inquiring people and all that… here we go.
Little Johnny you doun’t “have-ta-have” this but in many cases is cures some nagging problems…. and here’s the story:
You’ve see tires damaged by “cupping”, that’s those weird divits worn into your tire that makes a racket. Houw about driving along in your coach and on a predictibe time, the overhead cabinets shake…..BBBBBB……….BBBBB……..BBBBB…… at mabe a speed between 60 and 65 mph. OK so that tire may be balanced but it’s not “true”.
True means just what it says… the tire and rim together are actually and very round. It’s not that hard to make a truly round aluminum rim because they may be cut on a computer lathe. Steel rims may have a certain amount of “run out” but there is a tolerance in their manufacture. A rim can have some run out without effecting it’s balance and a bit too of it’s trueness but too much will cause whatever tire that’s put on it to wobble. Tires on the other hand are a molded part. By the nature of that molding process, there will always be a high and a low point of the mold made tire.
Now it’s very true that the new manufacturing processes have made newer tires much more “round” which brings that tolerance much less. In the good ole days, recapped tires came out square! Molded new tires had a much lower tolerance than today but still, if you treat a new tire to a true and balance process, that last 5% to an awesome ride is addressed.
Problem is it’s a dieing process… Amermach, made in good ole America in Americas Georgia is gone. They were the #1 truing machine manufacturer and the last to fall. Problem is after trying to explain why chewing off part of their gold plated tire, those that got it were fine but many just felt the process was barbaric and blamed everything that broke after that on those *&^^%$$@ trued tires.
In a word, if I am asked to rate a persons understanding the laws of physics… I would have to give them a failing grade. You cannot ignore the laws of physice, you can’t break them without consequences and they are totally irrefutable using the scientific method of understanding…. period!
Many look at getting a good ride in their car a black art filled with incompetent people who screw up everything they touch…. but in the case of truing tires that’s simply not true….. why you ask…. OK, follow me on this….. and for those that think this is a waste of time, you still may want to read this… what else do you have to do right now, the coffee is still warm….
The only way to produce any truly round anything is to run it through a lathe. The piece of wood or steel is stun and a cutter of some sort trims off the outside until it’s perfectly round. OK, so that’s what tire truing is.
The day started but I’m back…..
This is an Amermac 711 off the vehicle tire truing machine 
It was the most used truing machine on the market and is still top of the line. I purchased this truing machine for CLASCO Manufacturing in 1991…. it’s an old friend to me. A little worse for the wear now 
but our relationship is still strong. A tire is chucked up on the machine and as an idler wheel spins the tire I hand follow the tread cutting it round as the cutter moves across the tire 
This process is called a “90% cut” which means I trim the high 90% of the tread down to the lowest 10%. Here you can see a flat spot on this tire and how I’m trimming the rest of the tire to the bottom of that flat spot 
If you have ever locked up your brakes and skidded any distance you may have caused a flat spot like this. A truing machine can cut the tire back round. This is an extreme example but this is what the truing machine can do… the small out of round situation even caused on brand new tires can be felt sometimes and this machine is how to fit that.
Does it work? As long as the laws of physics hold true, a trued tire will not heat up, not cup on it’s own and the vehicle will by that virtue ride smoother which is a byproduct.
NOW, with the tire & rim assembly truly round, the old “gravity” or bubble balance which did not takr into account any out of round condition can be used to not only balance the tire at 3 speeds like the dynamic balancers only do, the tire will be round and balanced at any speed…. the laws of physics dictate that. 
On the spindle, the tire is let loose for the heavy point of the tire will roll the assembly to the bottom, that mark on the tire shows the opposite light point of the tire. Putting weights on that light side will balance the assembly where the tire/rim assembly is totally trued and balanced giving you the absolute best tire for your coach. The relationship of the 2 rear tandem wheels cause an out of true tire to effect the other tire causing a sympathetic vibration and a cycle which is what shakes the overhead cabinets.
The reason I have this machine and have been working it for over 20 years is the fact that the GMC motorhome rear suspension amplifies the out of round tire situation. We charge $30 per tire to true then balance your tires. End result will be longer tire ware, no cupping from balance issues AND the last 5% of the smoothest ride you will get on the highway.
See if there is anyone in your area has a tire truing machine, preferably an off the vehicle unit like the one we have. The on the vehicle cannot be as accurate because of the suspension tolerances. It might help but the real way is to true and balance each tire/rim assembly separately.
Hope this has been helpful, if you know anyone interested in this direct them to this post. let me know if you have any other questions.
Hey and thanks for reading all of this… I’m long winded … and your point?
See ya tomorrow…. .
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I am amazed had how smoothly my coach rides having had Jim perform this service when I got new Eagles and tires….nothing rattles inside the coach going down the road.