As long as it is in the tread belt, there are no real problems except
maybe the size of the hole. I recently had a flat fixed that had been
slowing losing air (had to fill it about once a month)  I did not use
vehcile daily and it would sit for weeks at a time on occaision so I
let it go. Recenty it started to leak faster so I went to have it
repaired and they found a nail near edge of tread that was long worn
down (I had made a trip to Colorado with it that way a few years ago
so I knew tire was sound otherwise) They told me that it could not be
patched and that I needed a new tire though it had 75% tread still so
I took it home and patched it myself and had it remoted and balanced
and I have had no problems with it as it does not leak a bit now and
it has made a 1000 mile trip since then too.
-----------------
The SnoMan
www.thesnoman.com

Tread area only, no closer than 1/2 inch to edge of tread area.
Speed rated tires lose rating when repaired.
The only approved way to repair a tire is to dismount it, through
inspection,
and the use of a patch/plug combination.  Its a patch with a plug applied
from inside.
The patch provides the air seal, and the plug seals the injury to keep
moisture and debris
out of the belt area.  Steel belts have a habit of cutting plugs as they
flex and then the
tire goes flat..  No tire driven on flat should be repaired. any signs of
cracking in the side
wall area or blistering in the liner area rule the tire repair out.
Repairing damage closer to the edges is not a good idea as the steel belt
may be damaged.

Here's a good link from Continental Tires
www.conti-online.com/.../www/us/en/continental/
automobile/themes/contiacademy/drivers_ed/tire_repair_en.pdf
Dunlap says
http://www.dunloptire.com/care/damage.html

Everything you ever wanted to know about tires
http://www.rma.org/
https://www.rma.org/publications/tire_service_professionals/index.cfm?Publicatio
nID=11335

Whitelightning

All tires are different. PA State Saftey Inspection Code states no
sidewall repair. Most tires are very clear as to what is tread and
what is sidewall. If in question, stay on the safe side and call it
unrepairable.
I deal in only 5 or 6 different style tires, all have wear bars. I
dont repair tread outside the wear bars by choice.

I hope this helped.

I looked at several of the tire manufacturer's web sites, and they all said
pretty much the same thing. The following is from
http://www.goodyeartires.com/faqs/AirLoss.html#3 :

"Is it safe to repair a flat tire?

"If a tire loses all or most of its air pressure, it must be removed from
the wheel for a complete internal inspection to be sure it's not damaged.
Tires that are run even short distances while flat are often damaged beyond
repair. Most punctures, nail holes, or cuts up to 1/4 inch -- confined to
the tread -- may be satisfactorily repaired by trained personnel using
industry-approved methods. Don't repair tires with tread punctures larger
than 1/4 inch, or any sidewall puncture. Also, never repair tires which are
worn below 1/16 inch tread depth. Your best bet is to make sure your spare
tire is always ready to do the job. Check it regularly for proper air
pressure and be sure that it is in good shape. If your car is equipped with
one of the several types of temporary spares, be sure to check the spare
tire's sidewall for the correct inflation pressure, speed, and mileage
limitations. See Goodyear retailer for expert tire repair."

The "tread area" is defined as the area between the inside edges of the
grooves on either side of the tire (i.e., the tread area does not include
the outer most tread block on the edge of the tire). See
https://www.rma.org/getfile.cfm?ID=645&type=publication for a picture
defining the tread area. The text associated with the picture follows:

"This graphic indicates that puncture repairs are limited to the tread area
as generally depicted in the graphic. DO NOT make repairs where the injury
damage extends into the shoulder/belt edge area OR where the injury extends
at an angle into the shoulder area. If there is any question that the injury
extends into the shoulder/belt edge area, then the tire must be scrapped."

You might also want to look at:

http://www.tiresafety.com/maint/maint_repair.asp
http://www.michelinman.com/care/buy_when.html
http://www.rma.org/tire_safety/tire_maintenance_and_safety/tire_safety_brochure/
tire_care_and_safety.cfm#replacement
http://www.conti-online.com/generator/www/us/en/continental/automobile/themes/co
ntiacademy/drivers_ed/tire_repair_en.pdf

Over the past 25 years i've not had a single problem repairing them RIGHT ON
the sidewall.  I believe it's a fabrication of lies by the tire
manufacturers to sell more tires.  At worst, a patch and a tube will allow
the tire to live out it's tread.

steve

If you gotta ask, ask your local tire store. If the tire can be fixed,
they'll fix it. I've seen more places try to fix a bad tire than refuse to
fix a good one.