Quote:
Originally Posted by davejay
Hey,
I run 245x65x19.5 tires on our 325. I don't like the skinny front tires. There's a lot of weight on the front end. A wider foot print gives you more stability. I run all the same tread on all 9 tires. Big trucks run snow tires in the rear for traction in weird places. Unless you plan on going off road, street treads are better. They are quieter, longer in mileage, wear better overall better suited for our application. You'll notice busses run street tires on all axles too. Traction is the big reason for heavy treading. My 245 s don't touch on the duals. That is a definite no no. Heat from the tread transfers to the sidewalks, thus blowout.
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I cannot find a 245/65 19.5 tires listed... did you mean 245/70?
Whilst I agree with you on the front axle loading, and cosmetics of the tire width, there are some other very important considerations.
Airstream and Cheverolet rate the P30 MH chassis under our 310/325/345 Motorhomes at 5,000lb.... so that is 2500lb per front wheel.
It is well documented that people have weighed their stock Motorhomes and been close to max or over max without too much gear onboard...
The Stock Alcoa width is 6", and there is a load rating stamped on my Alcoa wheels, of 2780lb.
I cannot seem to find the specs for the original Spec 8R 19.5 times, but I suspect it is about the same as the rim.
The closest and most common replacement for the 8R is the Metric 225/70 R19.5, and what it looses in overall diameter(33.1" vs 32.1"), it makes up for in load capacity. It is also wider than the stock 8r by some margin, and people who have swapped have stated it is more directionally stable too.
225/75 R19.5 "F" Rated tires can carry up to 3640lb single and 3415 dual @ 95psi. That is 860lb per tire over the capacity of the stock rim...
There is a "G" rated 225/70 option, that is weight rated at 3970lb per tire, but I see no logical reason to use those.
Then there is the subject of rim width.
Minimum manufacturer approved rim width for a 225/70 19.5 is 6" to 6.75".
Minimum manufacturer approved rim width for a 245/70 19.5 is 6.75 to 7.5".
Are you running wider rims than stock?
If not, I believe that there "maybe" safety/stability issues with running a 245 on a rim that is narrower than the tire manufacturer suggests... Not to mention the liability issue if you have a mishap, that is related to tire failure.
Each to his own, but I am, and will be running 225/70 R19.5 "F" rated, as it has more than enough safety margin and stability for me.
I'm not picking at you Dave, as you are not the only one I know who is running 245s... just putting it out there, so people know and understand, that the tire weight rating is not the limiting factor.