10 replies to this topic

[black98lx]

I'll need tires soon and want to swap to 15" wheels using the stock tire size. My question is do I need to change anything to keep the speedometer accurate?

[paulschott48]

Most tire places can look up the size up to go on new wheels. They will have to keep the outside diameter of the tire/wheel combo the same or really close. You are probably using 70 series tires (the height of the tire is 70% or the width) you will probably end up with 60 series. that way you can increase the rim and keep the same clearance by using the same width tire. my 98 se sport uses P205/60R 15's. The lug pattern is the same on all Contours as far as I know (I don't know all lol)

[black98lx]

Thanks for the info,but I WANT to increase tire diameter for fuel mileage reasons. So what I need to know is what changes if any need be done?

[spridget]

black98lx, on 31 December 2011 - 01:47 PM, said:

Thanks for the info,but I WANT to increase tire diameter for fuel mileage reasons. So what I need to know is what changes if any need be done?

Wheel diameter wont improve mileage. Increasing tire circumference will but the speedo will be off. There is no fix for that. Increasing wheel diameter will improve handling and appearance. To keep the speedo accurate you need a tire of equal circumference to the original.

[BuckeyeSVT]

To keep the same diameter but raise the size of the wheel... Here are your choices in tire sizes:

195/65R14 or 185/70R14 (Original Equipment)
205/55R15 (For 15" wheel)
205/60R16 (For 16" wheel)
205/45R17 (For 17" wheel)

Keep in mind these sizes keep the fact that this is not an SVT and the tires can't be too wide or they will rub when turning sharp. However, all these tire sizes will keep the speedo within 3% to keep the speed correct on the speedo.

Good luck, however I would recommend a low rolling resistance tire like a Michelin EnergySaver A/S or the Michelin Hydro Edge Green X..

-Dom

[black98lx]

Thank you everyone!

[99ContourLX]

FWIW, my Contour's Michelin Hydroedge tires have completed 52,000 miles with no issues.
I get them rotated and balanced every 6k miles. They still have 4/32 remaining.

[BrApple]

OEM tire size for an OEM 15" wheel is 205/60R15

if you want to go to a 16" wheel you would want 205/55R16 or 215/50R16.

And if you want a 17" wheel you would want 215/45R17 or 225/45R17.

Edited by BrApple, 08 January 2012 - 09:33 PM.

[BuckeyeSVT]

BrApple, on 08 January 2012 - 09:32 PM, said:

OEM tire size for an OEM 15" wheel is 205/60R15

if you want to go to a 16" wheel you would want 205/55R16 or 215/50R16.

And if you want a 17" wheel you would want 215/45R17 or 225/45R17.

Those are SVT sized, not SE. You do realize the SVT rack has limiters built in for wider tires and the GL/LX & SE racks don't? Please refer to my sizing post as those sizes will cause the least amount of problems.

-Dom

[BrApple]

Yes I am aware of the differences in the steering rack.

My SE stock came with 205/60R15. All the other sizes I listed are the correct plus 1 size for larger wheels based on this size.

I have used 205/60R15, 205/55R16, 215/50R16, 205/50R17 and 225/45R17 on my SE and SVT. The only rubbing issue I have had is with the 224/45R17 and the rear fenders. But this is because of the offset on the OZ Supperleggeras, iirc.

Edited by BrApple, 10 January 2012 - 05:00 PM.

[Delores]

Yes, larger diameter tires do improve fuel economy by changing the final drive ratio a wee bit... Enough to offset the cost of the wheels? Probably not.

There are on-line tire size calculators that will tell you the % error on the speedo (i.e 3%)..