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Discussion Starter · #1 ·
I am thinking of getting P225/55R-17 or P225/60R-17 size tires. These have a bigger diameter than the P205/65R-15 my car came with. Are there any issues with doing this, other than the speedometer being off a little? To keep the diameter the same with 17 inch rims, I would have to use P225/50R-17 or similar, and those tend to be more expensive, and probably somewhat harsher. Not to mention, the g3 wheel wells seem a little oversized with the standard tire size.
 

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I have used oversize wheels and tires with no issues. If you're going with 17" rims you may be able to add a 13" disc brake kit as well.

Handling is great with 16" wheels. My 3rd gen Sable had 15" rims, I switched to P225/60 R16 and have been very happy with this configuration. However if I had to do it again I would like to try 17" and get the large brake discs.
 

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Discussion Starter · #4 ·
While I'd love to have big brakes, 13 inch setup is just too expensive I suspect. I will upgrade to late gen 4 rotors with Hawk pads when once I get the rims though.
 

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While I'd love to have big brakes, 13 inch setup is just too expensive I suspect. I will upgrade to late gen 4 rotors with Hawk pads when once I get the rims though.
4th Gen brakes are a very noticeable and great upgrade ! One of the better bang for the buck investments. If you go with the 225/60 R16 setup there is slight rubbing in the front wheel wells. Not a big deal really if you don't turn or extend the steering all the way. But it is something to be aware of.

Monsoon
 

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Changing the tire diameter will mess with your speedometer and mileage. Just a heads up.
 

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Changing the tire diameter will mess with your speedometer and mileage. Just a heads up.
While the speedometer impact is true, gas mileage is either the same or has improved.

Keep in mind with larger wheels/tires your gear ratio will change but to your advantage. For example if cruising at 60mph was 1800rpm with OEM wheels, oversized wheels you'll be cruising 60mph with something like 1600rpm. Push to 1800rpm you'll most likely be traveling at 63mph.

Note the difference in the speedometer deviation because at 70mph your more like moving at 75mph. You can verify this deviation with a GPS unit that displays ground speed.

Keeper Kool....

Monsoon
 

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Discussion Starter · #9 ·
I will increase the diameter of my tire during the 17inch upgrade _only_ if I decide to have my ECU reprogrammed or chipped by that point, custom program to account for tire size of course. Otherwise I will use 215-55-16 or 225-50-17 depending on the rim (those are the recommended sizes to minimize the diameter distortion on our cars.)
 

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One more thing to consider. You don't want to increase the weight of the overall wheel/tire size too much from the OEM weight. If you can get a larger size wheel/tire for about the same weight you should be good. Use your original wheel/tire weight as a baseline to measure from.

Increasing the weight of the total wheel could reduce your acceleration time, due to the increased mass of both wheel/tire.

And with oversized wheels/tires wheel balancing is more critical as well.
 

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IMO larger tires are only a cosmetic change but cause a performance and $$$ penalty that is too much of a negative:Higher weight, stiffer ride, less resistance to impact damage, more $$$ for tires which usually have poor wear qualities, gearing change...ad nauseum.
 

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Nobody has mentioned putting more rubber on a stock wheel, like a 70 series tire...
 

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One more thing to consider. You don't want to increase the weight of the overall wheel/tire size too much from the OEM weight. If you can get a larger size wheel/tire for about the same weight you should be good. Use your original wheel/tire weight as a baseline to measure from.

Increasing the weight of the total wheel could reduce your acceleration time, due to the increased mass of both wheel/tire.

And with oversized wheels/tires wheel balancing is more critical as well.
Greater unsprung weight also impacts suspension, handling, and braking.
 

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While the speedometer impact is true, gas mileage is either the same or has improved.
I wasn't talking about fuel mileage, as I was implying odometer reading. ;)

I will increase the diameter of my tire during the 17inch upgrade _only_ if I decide to have my ECU reprogrammed or chipped by that point, custom program to account for tire size of course. Otherwise I will use 215-55-16 or 225-50-17 depending on the rim (those are the recommended sizes to minimize the diameter distortion on our cars.)
I do not know if the taurus's computer can change the displayed reading by using a reprogram.

One more thing to consider. You don't want to increase the weight of the overall wheel/tire size too much from the OEM weight. If you can get a larger size wheel/tire for about the same weight you should be good. Use your original wheel/tire weight as a baseline to measure from.

Increasing the weight of the total wheel could reduce your acceleration time, due to the increased mass of both wheel/tire.

And with oversized wheels/tires wheel balancing is more critical as well.
Increasing the total wheel package weight will require larger brakes. More weight, more rotating mass less braking power.

In addition to this, I fail to see how it would reduce acceleration time in a Taurus as there is no wheel spin to negate, instead the engine will be working harder to rotate the larger mass. However either way the difference would be negligible, either adding nor subtracting tire weight will not affect acceleration performance on this car.

IMO larger tires are only a cosmetic change but cause a performance and $$$ penalty that is too much of a negative:Higher weight, stiffer ride, less resistance to impact damage, more $$$ for tires which usually have poor wear qualities, gearing change...ad nauseum.
You're mixing larger TIRES with WHEELS.
I run larger WHEELS and as a result, I have to run LOWER profile TIRES. (but the wheel and tire combo are the same size as stock.) I run a 40 series (in my mazda) and this results in less resistance to impact damage.... however I do not see a higher weight, poor wear qualities and needing a gear change. (I do have a stiffer ride due to it being lowered.) But thanks anyways :)

Bigger tires actually add more cushioning so the ride is smoother, however they can add poor handling qualities due to sidewall flex (unless you increase rim diameter and reduce aspect ratio) they do have higher weight if you don't reduce the aspect ratio, and they (if aired correctly.) do not have poor wearing qualities. You shouldn't need a gear change unless you're jacking it up and putting 30" tires on it like a Jeep. You won't be able to fit tires large enough for a gear change on this vehicle without some form of serious modification.

Greater unsprung weight also impacts suspension, handling, and braking.
This.
 

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I ran 225/50ZR-16 on my SHO that are smaller in diameter than the stock tires. Acceleration was better with those tires and handled better with the shorter sidewalls. I installed 235/45ZR-17 on my OZ Racing 17X8 rims. The OZ rims were lighter than the stock slicers and so were the tires. I also lost 6 lbs of unsprung weight on each front corner upgrading to Baer Racing Sport 12.5" brakes with custom 2 piece rotors. The 2 piece rotors weighted 1 pound more than the stock 10.2" rotors and the modified hubs had 6lbs of material removed. The braking power and fade resistance was improved tremendously.

Bob

rotors:


Hub:
 

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Discussion Starter · #16 ·
One more thing to consider. You don't want to increase the weight of the overall wheel/tire size too much from the OEM weight. If you can get a larger size wheel/tire for about the same weight you should be good. Use your original wheel/tire weight as a baseline to measure from.
That's a good observation. Any ideas what's the weight of the factory 15 inch rims?
 

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What problem (if any) would I see going from a stock 215/60/16 tire to a 225/60/16?

Thanks.:)
Your better bet would be a 225/55R16 tire. It would give you a wider tire, still fitting the wheel well, and it's close enough diameter that you won't have speedometer problems.
 

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What problem (if any) would I see going from a stock 215/60/16 tire to a 225/60/16?

Thanks.:)
i run 225/60/16 on my gen4 (215 stock) and i dont think you will notice much of a difference. i run them b/c they are easier to find than 215s. and i buy used.


i would like to add 17s or 18s to my gen 4. at least 17s. but im a little confused...
if i get a 17" RIM with the correct profile/width tire to measure the same size as stock 215/60/16, and are close to the same weight. then i shouldnt have any ODO problems even with 17" rim size? if so is this possible as well with 18s?
if it does cause a problem with ODO. is there a way it can be adjusted to compensate?
 

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i run 225/60/16 on my gen4 (215 stock) and i dont think you will notice much of a difference. i run them b/c they are easier to find than 215s. and i buy used.


i would like to add 17s or 18s to my gen 4. at least 17s. but im a little confused...
if i get a 17" RIM with the correct profile/width tire to measure the same size as stock 215/60/16, and are close to the same weight. then i shouldnt have any ODO problems even with 17" rim size? if so is this possible as well with 18s?
if it does cause a problem with ODO. is there a way it can be adjusted to compensate?
You answered it. Yes, if you play with the profile (aspect ratio) you can put similar sized tires on with little to no difference. I do not know if the difference can be adjusted. But yes, if you play with the profiles correctly you can run a 16,17,18's. However there is a point where it's too thin, and causes problems.

Word of warning. Trust me I'm running on 18's right now (on my mazda) and they dent SUPER easy with a 40 A/R tire.

Use the tire size calculators to come up with the right tire size.

Just remember

The first number is the "Section Width" in mm's. The second number is the aspect ratio in %. the third number is the Rim diameter in inches.

There are math problems in which you can calculate everything....

Here's a good article to read.

Tire Tech Information - Calculating Approximate Tire Dimensions

They have other articles and can help you put together the right tire size to "Plus" your current tire size in which it will be the same diameter as stock with larger rims.;)
 
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