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Discussion Starter · #1 ·
Please see the below email sent me to by Jack Williams Tire:

Todd
Thank you for taking the time to email us regarding your concerns. At Jack Williams Tire Company, we strive to provide our customers with prompt and efficient service. I apologize that our Palmyra store did not call you back with the tire information that you were requesting. I have taken the liberty to speak with the General Manager and Service Manager from the Palmyra location. It is to my understanding that you were pricing tires which would wear longer, have better traction in the snow and were trying to find a tire size with more options that would fit your vehicle. The tire size for a Ford Focus ZX3 is 205 50R16, the vehicle could suffer damage to the over all computer control system if we were to install tires sized at 205 55R16 as stated by the Ford Manufacturer. A plus fitment for tires should be no more that 2-3% overall diameter. The difference between the two tire sizes is almost a full inch over the maximum capability. The manufacturer does not recommend any optional sizes for this vehicle. I apologize for any inconvenience this may have caused you and hope you can understand our position on this matter.

Best Regards
Janeine D. Kamora
Executive Administrative Assistant
Jack Williams Tire Co., Inc.
[email protected]


Can anyone shed some light on this situation??? Thanks in advance.
 

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I've put ~15,000 miles on my car with 205/55 16s (I run that size in the winter) with no ill effects...they're just being anal because its not the manufacturer-specified size. Plus I don't know where they're getting "it'll be a full inch taller" when a 205/55 tire has a 112.5mm sidewall, which is only 10mm taller than the 205/50 sidewall height of 102.5. I'd just go elsewhere...it sounds like they're really trying to cover their asses on this.
 

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yeah i run a 185/65/15 winter tire and 215/45/17 in the summer. the only difference that i know of is the speedo is a little off as well as my mileage readings. nothing that bothers me in one bit. . .
 

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I think you will find that there will be no possible chance of damage apart from the obvious.
The only time you have damage is when you have a car that has a computer controled differential. Case in point, I use to own a Nissan Skyline GTS4 (baby GTR) runs the same four wheel drive system as the GTR. Now I was warned that I had to keep all the tires the same size (diameter) and the worn size the same. This is because the ecu controls the drive in all 4 wheels measuring the speed, braking force etc etc. If by chance the tires were different the car would lerch down the road as the computer was getting false readings and would try to correct them. I am almost positive that the evo and sti will run a similar system with the same problems. As for the focus, thankfully (another thing to break) or unthankfully we don't have any such systems controlling the diff in our foci.
 

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i checked with that miata tire caluclator and the dif between 205/55/16 and 205/50/16 is only 3.4% circumference. so they are just being stupid. however, 205/50/16 is a very common tire size, it shouldnt be any problem finding tires in that size. was there any other reason why you chose a 55 series tire?
 

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55 series is a LOT cheaper, and has a much larger selection. if only using for winter tires it makes more sense IMO. . .
 

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I say for good laugh show up at the store with 20" rims and tires and tell them , the district mananger himself said it was o.k. to use these with no problem that should really get them going hehehe!!!!!!!!
 

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Discussion Starter · #8 ·
Everyone,

Thanks a lot for the quick responses and great feed back, I feel much better about the decision I made.

"thenorm", I chose the 55 series because it does indeed have a lot more options and they are cheaper. I went with the Kumho Solus KH16, 65 bucks from tire rack. Jack Williams wanted me to install a Toyo Proxe 4 for 125 bucks a piece, the sales manager said it would last roughly 25-30k miles. I cannot justify spending nearly twice as much money for a tire that will only last half as long. In performance applications I can see why someone would want to do that but my Focus is used primarily to commute me back and forth to work.
 

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Hahaha, what a load.

The computer cannot be damaged from larger tires, period. The ABS picks up wheel speed, and that won't be affected unless there is a different tire on each wheel, so thats not an issue (And if you did put on different sizes, it would just throw a warning light). And the ECU gets vehicle speed from the transmission. It doesn't know anything about tires. The only effect will be your speedo being about 2MPH slower, and your odometer would gain miles a little slower.

These guys need to take a class in computers before spewing such crap.
 

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Wow they are a smart bunch wonder where they went to high school "Hey sir my battery no good can I get a new one "you don't need one just hold it up to the light and let the sun charge it"
 

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As long as all 4 tires are the same size, there is no way the computer can tell what size is on the car.

Now if you run a larger diameter set on the front or rear, it may set an ABS code, but still, the computer isn't damaged.

On any vehicle with a limited slip differential, the exact same size should be run on the axle that has the LSD, as you will be increasing wear on the diff otherwise or even damaging it if the difference is great enough. This is a sore spot with '94-96 Impala owners, as the "full size" spare is actually a larger diameter than the regular tires. Running the spare on the rear will cause the diff to wear out sooner. This would hold true if you have installed an LSD on your Focus, for the front axle.
 
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