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Old 01-08-2022, 11:04 AM   #1
Don Scott
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Too much tire?

Hello everyone. My name is Don Scott and this is my first post. A question about tires.

My RV is a 1966 VW Sundial Camper. Curb weight of apx 2700 lbs. These are light, high profile vehicles. They are pushed around by cross winds and passing semis.

In order to mitigate this the bus crowd generally use a LT or higher rated tire.

In my quest, I picked the Thunderer Ranger, a commercial van tire. An 8 ply tire, rated at 2094 @ 65 psi. The original tires were a 6.40 - 15 bias ply. Air Pressure was 28/32 .

The Thunderers at 30/34 psi are stable and handle well, up to a point. Once at speed (65 mph) the tires feel "skatey", like they are not making full contact with the road.

What is the effect of running the tire at less than half of it's max pressure? Could these be too much tire for the vehicle weight?

My peers in the bus crowd run the General Grabber tires.

Lighter, different tread. In 205-75-15 they are rated 1609 lbs @ 44 psi, or 215-75-15 rated @ 1764 lbs @ 44 psi.

These tires have an all terrain tread where the Thunderers have a 5 rib tread design. Could the tread design have an impact?

Could the Thunderer Rangers be too much tire for a light camper van?

Thanks in advance for any replies. See you on the road.

Don Scott
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Old 01-08-2022, 11:11 AM   #2
jasin1
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Quote:
Originally Posted by Don Scott View Post
Hello everyone. My name is Don Scott and this is my first post. A question about tires.

My RV is a 1966 VW Sundial Camper. Curb weight of apx 2700 lbs. These are light, high profile vehicles. They are pushed around by cross winds and passing semis.

In order to mitigate this the bus crowd generally use a LT or higher rated tire.

In my quest, I picked the Thunderer Ranger, a commercial van tire. An 8 ply tire, rated at 2094 @ 65 psi. The original tires were a 6.40 - 15 bias ply. Air Pressure was 28/32 .

The Thunderers at 30/34 psi are stable and handle well, up to a point. Once at speed (65 mph) the tires feel "skatey", like they are not making full contact with the road.

What is the effect of running the tire at less than half of it's max pressure? Could these be too much tire for the vehicle weight?

My peers in the bus crowd run the General Grabber tires.

Lighter, different tread. In 205-75-15 they are rated 1609 lbs @ 44 psi, or 215-75-15 rated @ 1764 lbs @ 44 psi.

These tires have an all terrain tread where the Thunderers have a 5 rib tread design. Could the tread design have an impact?

Could the Thunderer Rangers be too much tire for a light camper van?

Thanks in advance for any replies. See you on the road.

Don Scott
I wasn’t aware that a 1966 vw camper van could actually do 65 mph….that might be the speed where it starts breaking apart….

Seriously though welcome to the forum ..it is a mainly fifth wheel / travel trailer forum but there are a few tire “experts”
I would think you would get better information on the aerodynamics and lift of a vw microbus on a vw website but hey why not…I’m sure someone on here has a theory ….good luck and welcome
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Old 01-08-2022, 12:25 PM   #3
flybouy
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Welcome to the forum. I dont know how relevant answeres will be here as it's a bit out of most folks experience. Generally speaking, I would be giving the entire suspension a good look and jot just the tires. A 56 year old micro bus converted to an RV that's basically built on a beetle chasis I think would be a handful @65 mph when new.


At that age all the bushings, mounts, shocks, etc would requie replacement. I'd suggest investigating upgradeing the shocks and upgradeing or adding, sway bars. The best tires in the world cannot compensate for worn suspension componets or make a vehichle capable beyond it's design parameters. Those buses were popular in Europe where speeds were much lower back then. The hippies liked them in the day for syrfing and partying in but don't think they were doing much speeding, at least not until they stopped.
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Old 01-08-2022, 01:11 PM   #4
sourdough
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As has been said, the forum deals primarily with RVs and tow vehicles so a VW bus is a little out of the norm.

That said we have some "mature" folks on here that might have some insight. I have never owned a VW of any kind (bus/bug, did own a Rabbit); thought I wanted one and a dealer let me take it to a football game about 100 miles away...in W TX. There was a gentle breeze that evening (for W TX) and I could not keep that thing in the lane - excruciating...and keeping at 65? It would have been a miracle to get to that speed and even more of one if we had survived the trip. Said NO to a VW.

My cousin's husband owned a VW van back in the 70s. It too was a handful to keep on the road so I'm not sure if tires are the answer. Marshall mentioned a lot of things that need to be checked and/or replaced on a vehicle that old. They were barely marginal new, don't have any idea how they wouldn't feel a little "iffy" at 56 years old.
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Old 01-08-2022, 02:48 PM   #5
CWtheMan
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My thoughts: Get a load inflation chart for your current tires. Set the individual tire pressures at a PSI value that will allow them to provide a 10% total load capacity above GVWR. That would be very close to today's tire inflation standards for automotive tires.
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Old 01-09-2022, 11:57 AM   #6
Don Scott
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tires

Additional information on the bus.

Owners manual state the max cruising speed of 65 MPH. This is based on engine size and transmission. Again, running bias ply tires.

My bus runs Bilstein shocks on all four corners and steering damper. Addco sway bars front and rear. New steering box about 30,000 mile back. Disk brake on the front, drums to the rear. The bus is mechanically very dialed in.

My question is regarding the tires.Is it a good idea to run tires at less than 50% of max inflation. Can a tire be to much for a light vehicle? Is the light bus not making full contact with the pavement. Is 5 rib tread better than the all terrain tread.

I know you can put too little tire on a truck (p metric passenger car tire of same size), can you put too much tire on. Thanks again.

Don Scott
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Old 01-09-2022, 12:12 PM   #7
JRTJH
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Quote:
Originally Posted by Don Scott View Post
Additional information on the bus.

Owners manual state the max cruising speed of 65 MPH. This is based on engine size and transmission. Again, running bias ply tires.

My bus runs Bilstein shocks on all four corners and steering damper. Addco sway bars front and rear. New steering box about 30,000 mile back. Disk brake on the front, drums to the rear. The bus is mechanically very dialed in.

My question is regarding the tires.Is it a good idea to run tires at less than 50% of max inflation. Can a tire be to much for a light vehicle? Is the light bus not making full contact with the pavement. Is 5 rib tread better than the all terrain tread.

I know you can put too little tire on a truck (p metric passenger car tire of same size), can you put too much tire on. Thanks again.

Don Scott

You are going to need to find a tire engineer, not an RV owner to get those kinds of answers. We have one "retired tire engineer" that is a member of this forum and he does post frequently. That said, the information you're looking for gets far deeper into the weeds than "RV tires".

Thinking "outside the box", if VW limits maximum speed to 65MPH, then "being pushed around by crosswinds at maximum speed" may not be a "problem" but rather "an expected outcome"...

Sort of like saying, "When I operate at the outer fringe of design, I get some control issues".... It may not be "tire related" at all, but "vehicle design related"... What happens when you operate at 55MPH?
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Old 01-09-2022, 12:31 PM   #8
sourdough
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You're asking some very broad questions without providing a lot of info. On the surface, yes, you can put too much tire on a vehicle but primarily due to mechanical problems. Heck, 1500 lb. off road vehicles run 44s without issue but they are mechanically modified for it. Yours has apparently been modified ??

Your tires support the vehicle, provide traction and roll. If the support of the tire is more than what you need for your particular vehicle air it down. Find the inflation chart for that tire and air up/down accordingly. You may need to fine tune a bit.

The type of tire, AT/MT/snow/summer etc. is dictated by how you use the vehicle; you have not shared that. Are you driving on a beach every weekend or trekking along our good 'ole U.S. highway system? On a truck lots of folks just go with a AT tire with a mild tread pattern. Personally I would not do that on a VW bus as the more aggressive the tire the more they tend to cause different kinds of issues - include getting "squirrely".

For your case with those tires I would think; 1) get the inflation right, probably overinflated and 2) you may need to get a different brand of tire. I've never seen or heard of that brand of tire and I can tell you from personal experience that some tires can themselves cause a vehicle to feel "skittish" or "skatey". But as I mentioned earlier, that is the nature of driving a VW bus so don't know exactly what you are dealing with. You could of course keep airing them down until you solve the problem but I doubt you would get much mileage out of them.....
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Old 01-09-2022, 12:52 PM   #9
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Also those old vw busses and bugs have weird tire camber don’t they? The back tires look like an odd angle…I imagine they have that factored into the suspension characteristics…with a heavier duty sidewall and wider tire then I imagine that will effect how it drives…especially at high speed…maybe very little actual tire contact in the rear

It’s like putting a big wide tire on a motorcycle

Honestly that van is best for taking the scenic route…not the expressway
Unless you swapped out the entire frame an suspension from a Porsche panamera
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