Tira wear

[Werner]

Hello.


I'm not a brisk driver.


Is it normal that 21" Firestone tires on the front axle are already down to 3 mm after only 8000 miles?


I live in a winding landscape and since the car doesn't like to drive straight ahead, I constantly have to steer it a little bit against it.





Best wishes to all and thanks!

 

[Gary WA]

Hello.


I'm not a brisk driver.


Is it normal that 21" Firestone tires on the front axle are already down to 3 mm after only 8000 miles?


I live in a winding landscape and since the car doesn't like to drive straight ahead, I constantly have to steer it a little bit against it.





Best wishes to all and thanks!

Check for any loose front end components. And also your toe in/out!

 

[Bill G]

I got about 14,000 miles from my last set of Firestone tires, also 21". The fronts on my car wear a little more than the rear although not much. I rotate the tires once in a while, but not on any particular schedule. My modern car tires wear a lot longer than the Model A tires. I think the first thing I would do is check toe-in and check to make sure all the ball joints are tight enough.

 

[nkaminar]

If your front tires are wearing faster than the rear then there may be something wrong in the front end, as everyone else said.

 

[MARKA]

Hello Werner ,
I suggest that next time you purchase Goodyear tires. My car has 19' inch tires and has done 10500 miles.I still have 5mm of tread left on all tires. I am very happy with them as the Rubber is still pliable and without cracks. The White walls are still white and have not yellowed at all.
Mark.

 

[ronn]

from everything read on these tire threads 10k seems to be about normal. Maybe diff for the radials. Cheap or expensive bias all seem to have similar results.

 

[Bob Bidonde]

The front wheel alignment needs adjustment. Toe-in is adjustable via the tie rod. Caster is fixed at -5 Degrees by the front radius rod. Camber is also fixed by the front spindles. Beware of a worn ball on the front radius rod which affects the caster angle. Also beware of a bent front axle which affects caster, camber & toe-in. Worn king pins & bent wheels also affect wheel alignment.

 

[Will N]

After you check the drag link and tie rod ends for wear and slop, the king pins and radius rod ball for wear and slop, and make sure your wheel bearings are not worn and the preload is set correctly, find a shop that works on trucks with solid front axles and see if they'll do an alignment for you. My Fodor's front end was all rebuilt and the toe in set correctly, but I was still burning through tires. I had a bent axle that the shop found and straightened. So far, the new tires are ok.

 

[talwrench]

I got 15,000 miles on my set of Firestones, Mostly highway high speed driving.

 

[Fullraceflathead]

If all of the front end components are in good shape you may want to add a slight more amount of toe in to improve drive ability.

 

[David in San Antonio]

Re: Camber - All modern cars have negative camber. The tops of the tires are closer together than the bottoms, to improve cornering grip. Our Model As have positive camber which makes the steering wheel easier to turn. Probably other effects too.

 

[nkaminar]

Some notes on caster, camber, and toe in (to expand on what David said):

Someone told me that spacers are available to bring the ball at the end of the front wishbone down to increase the caster. This is done to improve the handling. If you do change the caster, by fixing the ball and socket or adding a spacer, adjust the toe in afterwards. Because of the camber, changes in the caster will change the toe in a little bit.

Modern cars have negative camber because during corning the wheel on the outside of the turn is upright and the tire in full contact from side to side. This is because of the independent suspension that modern cars have. Racing cars have more negative camber.

For the Model A, the caster is positive because that puts the center of turning at the center of the tire and that makes turning easier.

 

[arnhemmer]

Also check the tie rod to see if it might be bent. I hit a pothole soo hard one time it actually bent the tie rod. Didn't notice it untill I saw the tire wear.

 

[CWPASADENA]

I got 20K miles on a set of 19 inch Goodyears. I watched the toe settings and rotated them a few times. Probably 10 K of that was long distance touring.

Chris W.

 

[JayJay]

I think that an unrecognized or perhaps underevaluated issue in Model As is bent front axle. If the axle is bent it won’t steer properly no matter how good the rest of the suspension is. This can be due to collision or maybe even normal wear over 90+ years of driving, many on unpaved or highly crowned roads. In the course of restoring my ‘30 I had the opportunity to evaluate six front suspensions. All of them had bent axles to one degree or another.

There are two things to consider - bend and twist. If you lay a straightedge (a six foot carpenter level works well) across a bare axle then it should touch at the two spindle bosses and the two spring perch bosses. Check both sides. Straighten gradually with a hydraulic press, cold. I used a 20 ton press from Harbor Fright and it works fine. I put a piece of steel on the web to press against, not the flanges.

Next is twist. You need to borrow or make winding sticks. I took some 1” steel round rod, tapered the ends to 15 degrees in the lathe, and center drilled 3/8”. Make eight of them. You then insert 3/8” solid rod (mine are about 3 feet long) and snug the tapered adapters into the two spindle holes and the two spring perch holes. String across the tops of these sticks and that will tell you where the twist is. Again cold, use a pipe wrench and a long cheater bar to gradually remove the twist. Check again for bend when you are done.

Using this method, we were able to straighten four of the six bent axles to perfection (the other two were in cars and unavailable).

And don’t forget to check the wishbone. Both arms should be dead nuts straight with no bow. I’ve seen perfect wishbones on bent axles, so the two don’t necessarily go together.

 

[rotorwrench]

I have a lot of experience with the 16 to 19-inch motorcycle tiress. They are narrow by comparison to the automobile tires. The compounds used vary depending on if it is a sports tire or a touring tire. The touring types wear better but they all wear down with use and not nescessarily hard use either.

I have no idea what compounds are used on reproduction tires but it can sometimes be apparent on how well they handle on the road. Tires that skid easily are generally a harder compound that those that don't. I don't worry so much about how fast they wear down as I do on how well they perform. The truer the wheels are, the balance of the wheel assembly, and the condition of the alignment are key to a good longevity as well as the road conditions. If the tire is worn from say 9 or 10mm tread depth down to only 3mm left over in 8,000-miles then that is a bit concerning. Either the tire compound is on the soft side or there may be issues with road surfaces. If a car wears front tires out more than rears then the steering or mechanical condition of the front end is suspect to a degree. All four tires should wear evenly in a perfect world but there are a lot of factors against that notion.