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Old 09-19-2011, 12:41 PM   #1
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Changing tire size?

We are towing an 08 Scion XD behind our motorhome and getting ready to replace the 195/60R/16 OEM tires. However, there seems to be limited tires in that size, so far only one Iíve found, Bridgestone Turanza, which I donít want to use since it is the OEM and hasnít done too well. There are other tires such as a 205/55/16, a 215/60/16, a 215/55/16 and a 225/50/16 which according to Discount Tire will fit the Scion. I guess these are considered to be low profile tires? My question is will using one of the optional tires adversely effect the angle of the tow bar or cause me any problems towing the car?

Comments and thoughts appreciated.

Thanks,
RJ
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Old 09-19-2011, 03:15 PM   #2
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What you are concerned about is the diameter of the tire. If this changes too much it will change the angle of the tow bar and cause problems.

That being said, in order to change the height of the tow bar attachments by 1 inch, the tire diameter has to change by 2 inches. This means that if the tire is 2 inches taller the tow bar attachment will rise by 1 inch, conversely if the tire is 2 inches shorter the attachment will drop by 1 inch. NOTE: rarely will any tire companies recommend a tire that is 2" different in height.

If you want a very close match go with the 205/55R16 (drop 0.5") or the 215/55R16 (rise 0.1"). The 215/60/R16 is 1" taller.

See the following for a tire calculator: http://www.1010tires.com/tiresizecalculator.asp
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Old 09-20-2011, 08:01 AM   #3
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Alvin,

Thanks for the info. I checked the site you referenced and if I'm reading it right it looks like the 215/55R16 has the least diameter difference, 0.4% where the 205/55R16 has a 1.35% diameter difference. Based on these figures wouldn't the 215/55R be the better choice? Thanks again for your help.
RJ
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Old 09-20-2011, 11:44 AM   #4
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Either one will work, the 215 is approximately 3/4" wider than the 195.

What is the cost difference between the 205 and 215? Are there any clearance problems with the 215?
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Old 09-20-2011, 06:51 PM   #5
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Going to Discount Tire tomorrow & will check prices and clearance concern. Thanks again.
RJ
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Old 09-21-2011, 07:01 PM   #6
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Quote:
Originally Posted by RJEV View Post
My question is will using one of the optional tires adversely effect the angle of the tow bar or cause me any problems towing the car?
Going from 195/60R16 to 205/55R16 is going from 4 choices among 3 brands to over 150 choices among 14 brands at TireRack.com. I'm a Michelin fan, and Michelin has 22 different tires available in size 205/55R16 at TireRack.
Tire Search Results

The specs show the 205/55 is 0.4 inch shorter and a hair wider than the 195/60, so it will lower the front of the car about two tenths of an inch. That shouldn't be enough to affect your tow bar.

You care about diameter of the tire, but the accurate way to measure the impact on your drivetrain is use the specs to find out the tire revolutions per mile (revs/mile), and compare.

195/60R16 has 823 revs/mile. 205/55R16 has 836. 836 revs/mile minus 823 = 13. 13 divided by 823 = 1.58 percent difference. Therefore, your speedo will be different by 1.58 percent, or about one MPH at highway speeds.

So if you want more choice of brands and tread with minimal impact on the performance of the vehicle,, then go to size 205/55R16.
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