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Can shaving tires cause severe out of balance?


thonczarenko

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I have a Toyo RA1 shaved 4/32 and needs 5 oz to balance. Previous tire on this wheel only needed 1 oz total.

 

Could it be a bad tire, or does/can shaving a tire cause this issue? If it is from shaving, is this acceptable or should the tire be returned?

 

Thanks,

Todd

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Some tires just don't balance well with some wheels, shaved or not. I've mounted tires on my TE37s that didn't need any weight to be "balanced" and different tires on the same wheels that needed upwards of 40 grams for a single plane static balance. Tires are rubber and far from perfect.

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  • 4 weeks later...

Ive run into this before and we broke the beads on the tire and rotated the tire 180° on the rim. I took several ozs. off what was needed to balance the tire.\

 

YMMV

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It's a combination of things, wheels,tires and balancing operator. 5oz. on a shaved 17" is not terrible. Spin it 180 degrees like it was mentioned.

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Does Toyo paint a colored dot on the tire to identify the heavy spot of the tire?

 

Some motorcycle tires do that so you know to rotate the tire/dot opposite the valve stem for better balancing.

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  • 10 months later...

A good tire tech will automatically rotate the tire 180* on the rim and balance again. To even sit and ponder such a thing without reorientation of the tire and rim is just lack of sense. This would be the best indicator that you need a new tire shop. (For those taking their loose wheels/tires to a local shop).

 

To question if balance is going to be different after taking a knife to a tire is kind of a silly question. How can it not? Is it a problem? No.

 

Best of luck.

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Note that your tires will rotate on the wheels after a few track sessions; sometimes a lot, sometimes a little. On my Mustang, the rears rotated more under acceleration than the fronts did under braking. In either case, any "precision" balancing will go out the window quickly. With that being said, my next move is to balance only the wheel/valve assemblies and just throw tires onto them.

 

Mark

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Here are the results of some testing that I did at PBIR back in December 2010. Photos are probably not visible to viewers who are not Corner-Carvers.com members, so I uploaded the photos elsewhere and linked them.

 

http://www.corner-carvers.com/forums/showpost.php?p=878099&postcount=26

 

FWIW, here are some photos of my tires after 4 NASA Time Trial track sessions on a Saturday. The critical information is listed in the photo captions. Ignore where the tires seem to be mounted in the photos, as they were taken on Sunday morning after being cross-rotated on Saturday night. At this track (Palm Beach International Raceway), curb jumping is not an option like it is at Sebring. It has 2 very long, right-hand turns and 1 very long, left-hand turn. Not an exciting facility, and it's very hard on tires without providing much grip.

 

300x300.jpg

 

Note that this was a used set of tires (2 previous track days) that were only flipped around on the wheels when they were mounted/balanced the previous Friday. The mounting/balancing was done by a local Napa shop that tinkers with Spec Miatas on the side, although I don't think these tires got any special treatment in regards to using a minimal amount of lube to seat the beads, etc. However, I did not see any excessive lube on the sidewall or wheel lip when I picked them up from the shop, so maybe they did go lightly.

 

Unless an arrow is drawn on the blue tape, assume that the yellow line was aligned with the center of the tape after each session. I drew a brighter yellow line over the true yellow sidewall chalk line in MS Paint for clarity.

 

SAT 1 = Saturday, after session 1, location of yellow line

SAT 2 = Saturday, after session 2, location of yellow line

SAT 1-2 = Saturday, after sessions 1 and 2, location of yellow line (did not vary)

SAT 1 2 3 4 = Saturday, after all 4 sessions, location of yellow line (did not vary)

etc...you get it.

 

This was just an experiment to see how much R-comp tires move around after a typical mounting/balancing job. I was surprised to see that my fronts basically did not move, after observing significant front movement on a 2011 Mustang GT with Nitto Invo tires on stock 19" wheels in HPDE-3. My 2004 Mustang has 13" SN95 rotors / 2000 Cobra R Brembos / Carbotech XP-10 pads up front and stock SN95 rotors / stock SN95 calipers / Carbotech XP-8 pads out back, while the 2011 Mustang has the 14" Brembo package up front with stock brakes in the rear; pad compound for this car is unknown. I can confirm that my car is driven much harder and quicker than his, though.

 

After cross-rotating the tires on Saturday night (LF/RR swap, RF/LR swap), there was noticeable (yet understandable) vibration in the front end, although it only lasted a few laps. By the end of the day on Sunday, the front tires had not appreciably rotated from where they started, and the rear tires had rotated less than the day before.

 

My preliminary conclusion is that tire balancing is not 100% necessary or effective unless you have a foolproof way to prevent them from rotating on the wheels. In my case, it will save about $5 per tire, and I have them flipped on the wheels after every track weekend. If anything, a compromised alternative might be to balance the wheel itself and then mount tires without further balancing. YMMV.

 

While this particular set of tires was corded by the end of the weekend and will not be re-used, I will attempt to document the new set of tires after using hair spray to mount them (which might be a couple of months).

 

Mark

 

300x300.jpg

Note: In the photo above, the yellow chalk line was probably not aligned properly with the valve stem.

 

300x300.jpg

 

300x300.jpg

 

300x300.jpg

 

Note that the fronts didn't rotate much from braking. The LR only rotated a few inches, while the RR was out by more than 90*.

 

Mark

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  • 1 month later...

FWIW, at a recent event at Sebring, I only had my bare wheels balanced, while the tires (used CTSCC take-offs) were installed last with no further balancing. As I was focused with just being on track for the first time in 3 years, I completely forgot to mark the sidewalls and wheels to determine if any tire rotation was present. However, I can say that I noticed no odd tire vibrations throughout the weekend from not being perfectly balanced. Note that my tire guy said that he needed nearly 80 psi just to seat these tires on the beads, so I'm somewhat confident that there probably wasn't much tire rotation.

 

Mark

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