On my fenderles av8 roadster i have 500/525 x 16 front and 750 x16 rear firestone deluxe champion bias ply tires. I had some bounce/ shake in the front a 50 to 55 mph. Everything is tight and balanced. When playing with tire pressure i found that the lower i go the more shake i got. I am now at 32 psi and the shaking is much better. I like to inflate a bit more but factory days max 32 psi. Will i get in trouble when go higher ? I dont want to risk a blown tire at highway speed. Annyone drive them with higher pressure at highway speed ?
I can't imagine why, they would be like rocks. These tyres are often referred to as potato shaped... not round. Perhaps if you could get them shaved into a round shape you would not need excessively high pressures on such a light car. I suspect the high pressure is masking the real problem.
I imagine X38 is correct about masking the real problem. In any event, I would not exceed the manufacturer’s recommended pressures. They’re there for a reason.
The higher pressure is possibly making them round as opposed to egg shaped at lower pressure. I remember when getting new tyres fitted they would purposely overinflate and then reduce to the correct pressure.
Have the tyres been dynamically balanced? Bias plies tend to change shape a hell of a lot more than radials, making some of the dynamic balancing process not as effective (as an aside, race slicks are even worse in that regard). It may be worth your while throwing the wheels onto a bubble balancer and see how far out the static balance is. Cheers, Harv
One concern is tread wear at the contact point ( patch ) which becomes smaller as the pressure increases. The pressure goes up as operating temperature rises, due to friction and flex heat. The real concern though is while turning you are depending on the steer tire to guide you through the bend of the turn. If the surface of the pavement has residual oils, water, or is just dirty; use of the brake can turn your car into a sled especially should you need to use the brake. Myself, if faced with this problem I would research my region for the front end guru ( they are getting to be fewer and fewer ). Then cut loose some cash for the opinion of a seasoned pro. The failure of loosing it in a turn is devastating.
I had the SAME problem, my front tires would bounce like basketballs I replaced tires, king pins set and reset toe-in etc... I then added more front tire pressure all the bounce is gone if I keep 30 psi or more, I have run 35 at times with no problem. I don't think a couple of pounds will hurt, my gauge could be off by that much.
Not death warble. Death dribble. Install a heavier engine, like an early hemi Find a heavier girl friend or maybe add a supercharger
Hello, Wow, a Firestone Tire with the same problem as from back in 1958-68. The whole concept of factory tires as being the “end all” for smooth running was a well know like/dislike from those early days. Our neighborhood tire store stocked all of the good brand tires and even the old Ford parts dealers had the popular sizes for their displays and sales. 1958 Lion’s Dragstrip entrance The Firestones came from the factory on our 58 Impala and as neat as it looked, there were some high speed wobbles and funky handling at times. (Not so noticeable in a quarter mile full acceleration) Countless road trips were questionable due to the wobbling. Balance and alignment are the first things anyone, including our neighborhood tire store suggested, including minimum and maximum pressure in each tire. But, as specialists in all fields sometimes have a better idea, an alignment place in Los Angeles told us to go to this little converted gas station near the downtown City Hall building for a true event. A true event? A @themoose completed Impala, the 65 El Camino and 327 powered sedan delivery have all gone to the same true event in Los Angeles, over time and in their heydays. We have all learned a lesson from the countless tire stories, including proper balancing, matching tires, alignments and other bits of information. Degrees, angles, new parts, all play a part, but the one thing most forget is that not all tires, even new, are perfectly round. No amount of balancing with custom weights, taped or hammered in place is going to override a fact of nature. We cannot drive on “caveman square wheels,” so to speak. They have to be round to then get balanced and aligned. Jnaki Truing is taking off the not round portions of the circular tire to give the rim/tire combination a smooth round rotation. Don’t be dismayed at how much you spent on the tires and how much rubber is shaved on the ground below the spinning tire. It works and we all have to give up a little to get a lot more in better driving abilities and handling. Then, the countless forms of tire balancing can begin. And as a final step, wheel alignment. Not all tires, even from the USA made factories supplied to all cars are perfectly round and could cause effects as shown and discussed. YRMV The one good thing for Firestone carcasses, they were valued by all tire recapping services as being one of the best trade in carcass tires. The Inglewood Tire shop (Pos A Traction -Redline tires) gave discounts if the trade in tires were Firestones.
No, they won't blow up if you go a bit over the recommended maximum pressure. you should see what kind of pressure they run at Bonneville
Nice looking ride. I'd rig up a pointer fixed to the floor. Coat hanger and a concrete block, or anything. Gotta measure the gap, not just eyball itanything. Max tire runout 3/32" / 0.09" on the tread road contact surface. Sometimes it's the tire, and sometimes the wheel, and sometimes both . Re-clocking the tire on the wheel can improve things a lot, sometimes. Lug centered wheels have two strikes against them when it comes to wheel tire runout. Hub centered are way better.
I'd always assumed that the overinflation was to make sure that the bead was fully seated on rhe rim.
I remember my father had a set of Firestones on a new '68 LTD.......had them on the car for about a week and ran to replace them with a set of Uniroyals....if I remember right they were terrible in the rain....never ever got a set of Firestones again!
The tyres on the front of my HA/GR in the avatar are 13" crossplies. Admittedly the frontend is light but I inflate them to 35 p.s.i. so the contact patch is smallest. Been doing it for nearly 10 years now.
New tires are not round! Doesn't matter what brand, what price, radial or bias.... I learned from an alignment craftsman that the best thing you can do is: Inflate to the max pressure Drive them for at least 500 miles, with enough long drives to build some heat in them Check for roundness (shave if necessary). Check wheel radial runout and side runout Balance Tires will stretch and grow until they get to where they need to be (just think of how distorted they get... taken from a mold when hot, stacked, wrapped, piled a mile high in a warehouse and shipping...). Once they 'normalize', you can do something with them. Maximum inflation is based on the maximum allowable load (load rating). The lighter the load, the less pressure required to maintain a correct contact patch. The offsetting factor is... the more sidewall flex (due to low inflation), the more heat is generated within the tire carcass. Also, the more heat generated, the more the air expands, so pressure goes up. Catch 22? Not really.... Just find the optimal pressure to get the contact patch and ride quality you want. But, as stated above, high air pressure turns a tire into a beach ball!
Some tires, especially old design bias ply, get a "flat spot" on the place where they sit if unused for a extended time. The cure is to drive on them for for a while, the tires return to round, and the vibration goes away. The increase in tire pressure would lessen will reduce the tendency for a tire to distort and get a flat spot consistent with your observation.
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