Flat Spot - Toyo Proxes S/T

[we350z]

Took my X into my wheel guys this morning to diagnose the steering wheel vibration I have been experiencing lately. Apparently both my front tires have flat spots. They are the Toyo S/T 275/20. They were able to match the passenger side tire on the wheel to 17lbs. road force however the driver side is @ 54 lbs. which is way to much runout at .029".

I am going to check with the place I bought them about warranty coverage but I doubt they can do anything for me. My other car had a problem because i had a bent rim i replaced and the tire had molded to an irregular shape. This has gotten a little better as I put some more mileage on it but isn't as extreme as the X. I may just get a new tire for each vehicle.

The reason I got the flat spots was from letting the car sit to much, though most of the time the wheels were either off the car or suspended in the air. Anyway I am going to try and give them a good workout on the local twisties to heat them up and work them out good and see if it improves at all. Most of the time I drive the vehicle very short distances which doesnt give the tires much use or much time to straighten out.

Anyone know of any other tips before I bite the bullet? This sucks. I am just plagued with tire issues.

[motordavid]

Sorry to hear but in my experience with a car or two and, 3 m'cycles
"sitting", I've never had a flat spot problem.

I pump up the "sitting" vehicles to near max pressure...some sit for
5+ months. But, it could happen, I suppose. A good long trip with
some twisties is worth a try.
GL,mD

[we350z]

i dont think i had max pressure but it was up there 44psi or so

[TowX]

There are really only 3 ways to flat spot a tire:
1- lock up a wheel when braking. which is virtually impossible with ABS
2- put the car into a skid whhich would laterally flat spot a tire. Again hard to do with all the electronic nannies in our cars
3- damage a belt in the tire.

A lot of tires will develop a temporary flat spot if left for a number of days. Especially prevalent with tires which have nylon belts, Pirelli being the worst at this. But once you drive the car and get the tires up to temp, the belts round out again. Usually.

Two suggestions-
First, for the tire that still showed 54 lbs after RF, was it all in the tire or any movement in the wheel? I'm assuming they tried spinning the tire on the wheel per the RF readout, and the best they could do was 54lbs? If it's all in the tire, and the wheel itself is perfectly true, then the tire should have been hopping on the machine. That's a lot of imbalance! I had a slight vibration on one of my rear 19" Michelins, but at it's worst it was only 15 lbs. Properly spinning it on the wheel got it down to under 10 lbs, then balance it and it's smooth as glass.

Go take your nice long run in the twisties, put 50 miles on them, then go straight to the tire shop and have them RF'd again without letting the truck sit too long. Also, the Hunter RF machine can be sensitive to centering the wheel. Most tire guys take the easy way out and stick the centering cone in from the outside. Think about it, that's where the center cap goes and isn't a precise hub-centric machining like the back bore. My guys always cone from the rear of the wheel, just like the way the wheel is mounted on the car. They have to be especially careful to not scratch the face of the wheel with the outer locking ring, but if they do it this way, you get the most precise readings.

After all that, if there's a "flat spot" on the tire, I can't for the life of me think of a cause that wouldn't be a tire defect. The nylon belts don't have a permanent memory so a belt deflection generally isn't permanent. More likely a broken belt. Good Luck

[we350z]

Thanks man you know your shit, or least talk a good game lol. I will try your advice. My initial thought was that most modern tires are not susceptible to to permanent flat spots as old steel belted only radials were. Toyo will replace the tire for excessive road force only withing the first 1/32" of tread wear.

I don't think they are dicking me, my wheel guys are really good and do a lot of upper-end shit like lambos and stuff.

They use the laser hunter machine to match the wheel to the tire for optimum road force. Here is what my printout reads:

Road Force
Tire - 54 lbs.
Assembly - 49lbs.

Diagnosis - ForceMatching will not bring assembly within limit. Use tire on a differernt rim.

Rim: Pass

All runouts are well within spec with the exception of the top one on the picture which reads .029".

Originally Posted by TowX

There are really only 3 ways to flat spot a tire:
1- lock up a wheel when braking. which is virtually impossible with ABS
2- put the car into a skid whhich would laterally flat spot a tire. Again hard to do with all the electronic nannies in our cars
3- damage a belt in the tire.

A lot of tires will develop a temporary flat spot if left for a number of days. Especially prevalent with tires which have nylon belts, Pirelli being the worst at this. But once you drive the car and get the tires up to temp, the belts round out again. Usually.

Two suggestions-
First, for the tire that still showed 54 lbs after RF, was it all in the tire or any movement in the wheel? I'm assuming they tried spinning the tire on the wheel per the RF readout, and the best they could do was 54lbs? If it's all in the tire, and the wheel itself is perfectly true, then the tire should have been hopping on the machine. That's a lot of imbalance! I had a slight vibration on one of my rear 19" Michelins, but at it's worst it was only 15 lbs. Properly spinning it on the wheel got it down to under 10 lbs, then balance it and it's smooth as glass.

Go take your nice long run in the twisties, put 50 miles on them, then go straight to the tire shop and have them RF'd again without letting the truck sit too long. Also, the Hunter RF machine can be sensitive to centering the wheel. Most tire guys take the easy way out and stick the centering cone in from the outside. Think about it, that's where the center cap goes and isn't a precise hub-centric machining like the back bore. My guys always cone from the rear of the wheel, just like the way the wheel is mounted on the car. They have to be especially careful to not scratch the face of the wheel with the outer locking ring, but if they do it this way, you get the most precise readings.

After all that, if there's a "flat spot" on the tire, I can't for the life of me think of a cause that wouldn't be a tire defect. The nylon belts don't have a permanent memory so a belt deflection generally isn't permanent. More likely a broken belt. Good Luck

[TowX]

Spent a few years with Goodyear a number of years ago, so kinda know my way around tires. That and I spend way too much money on wheels and tires for all the toys. I'm lucky that I have a friend who runs a local tire store who knows what he's doing and has good help. Most of the BMW/ Audi and some local Porsche folks use him for everything.

Hopefully your guy can do something for you. At least he can call Toyo and ask for assistance. Clearly not a wheel issue. And if parking it was going to cause a flat spot, you'd have all 4 tires flat spotted the same way and you don't.

[we350z]

Yeah. Well first off the did dismount the tire, check that the wheel was in round and balanced itself and then of course matched the low point of the tire to the high point of the rim using the Hunter. So they spun the tire to get the lowest road force. No doubt they know what they are doing that is why i go there. As for the people I bought it from they told me if it's within 1/32" of the tread 100% replacement otherwise NOTHING. Also this model was abruptly discontinued so IF i qualify for replacement they will replace one 100% and prorate the remaining 3.

I guess I need to measure the tread depth but is that not what the .029" runout means for the tread? If so I am just under what I would need to qualify :-(

Originally Posted by TowX

Spent a few years with Goodyear a number of years ago, so kinda know my way around tires. That and I spend way too much money on wheels and tires for all the toys. I'm lucky that I have a friend who runs a local tire store who knows what he's doing and has good help. Most of the BMW/ Audi and some local Porsche folks use him for everything.

Hopefully your guy can do something for you. At least he can call Toyo and ask for assistance. Clearly not a wheel issue. And if parking it was going to cause a flat spot, you'd have all 4 tires flat spotted the same way and you don't.

[we350z]

I also called Toyo customer service and they told me the same thing.

[we350z]

Well guys it looks like Toyo might be buying me a set of Proxes S/T II's:

11/32" = .34375"
- 01/32" = .03125"
10/32" = .31250"

I measured with my digital micrometer to .318-.320". That means I have approximately 92% tread left and they should pro-rate the other 3 by that much. So I'm guessing that might end up being $100 or so cost to me?

I'm going to double check my measurements but I think I may be in the clear here.

[we350z]

ne1 got s/t II's? Pictures? Feedback?