Tread gap on inside only?

I have a 2000 Focus SE. Replaced factory tires at around 60,000 miles (+/-) with (forget their name now....Goodyear maybe. The guy said the tires they sold me are pretty much the exact same as the factory ones)
at NTB. First problem, I noticed that the steering wheel would vibrate very rapidly back and forth at speed. I knew this to be from bad balancing. I took it back and had the tires balanced and it helped just a TAD. I also noticed that when slowing down and eventually coming to a stop, there was this rythmic, thumping noise (usually a sign of a defective tire(s)). I rotated the tires myself and all problems disappeared!!! So at this point, I know I probably have poorly balanced tires and maybe defective as well. (I got the warranty from NTB).
Here's the really weird thing though.... I noticed that all 4 tires have a noticable gap between the first and second tread on the inner part of the tire. It's nearly twice as wide as the gaps between the other tread on the tire: (crude example below)
X__X_X_X_X (X's are the tread and _'s are the valleys between the tread). And yes, I have my tires rotated every 6K miles.
I never really noticed this before, is this normal? Should I take my findings about the vibrating and thumping noise going away after I rotated the tires AND this tread issue back to NTB and get the tires replaced under warranty? Any NTB workers in here? Will they replace the tires or give me crap?
Thanks
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On 18 May 2005 05:32:02 -0700, snipped-for-privacy@hotmail.com wrote:

If all the tires have ths same gap between the tread pattern, then I'm sure that is part of the design. If you look at all the tires available out there, pretty much no two will look the same. It's all in what the engineer/designer thought would work best.
It sounds to me like you have a problem with one, or maybe two tires. It could be a defective tire or poor balance job. Wherever the tire was originally placed on the car made the problem very pronounced and when you rotated them, you put it at a place less noticed. (Past experience has shown me that front locations telegraph problems more, while rear placements mask problems.)
Check your wheels for balance weights. Do some or all have really big chunks of weight attached? If you have three with small to medium sized weights and one with a really big chunck, the wheel with big chunck is probably the problem. If you find a situation like this, you can ask the tire store to rotate the tire 180 degrees on the wheel and rebalance it and see if it requires less weight. That could cure a problem caused by an technically in-spec, but marginal balance job.
If you actually have a defective tire, I'd suggest rotating the tires back the way you had them, and then try taking off first one front wheel and then the next and run your spare in that position. If you run the spare on the right front and the issues go away, then there is your problem tire. (Obviously check the back wheels in the same fashion if you didn't find a problem with the fronts.)
As for dealing with NTB, I can't help you. I will say though that most chain store businesses won't quickly admit fault/fix problems unless you can back up your assertions. I don't know who teaches these people, but it seems the theme is the same: the customer is an idiot and doesn't know what he is talking about. If you do a good job of troubleshooting and push as hard as you need to, you will likely be taken care of.
Matt Focus owner
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