[sactruck]

I recently put 18" wheels and tires on my Terrain that originally came with 19" chrome wheels. The 18" wheels and tires came from another terrain (I purchased them on E-bay) and stiil had the original pressure monitors in the wheels. When I put the new wheels on the Terrain the vehicle would not recognize the sensors in the new wheels (the sensor I.D. numbers have to be programmed into the cars computer by the dealer). I did not bother to have the sensor numbers programmed since the Terrain will only store one set of numbers at a time and I do not want to have to program the sensors everytime I put the 19" wheels on the car in the spring. The downside was that the Terrain indicated on the dashboard display that the monitoring system was inoperable (error could be cleared by pressing the up or down arrow on the center stack) and a yellow warning light was indicated in the speeedometer. To my surprise after driving a few hundred miles the Terrain no longer indicated that the monitoring system is inoperable and the yellow warning light is also not activated (The tire pressures will still not indicate when the tire pressure menu is displayed). It appears that after driving for a number of miles the Terrain must deactivate the warning systems which in my circumstance is a good thing.

 

[sactruck]

The switch from the 19" to 18" wheels does change the speedometer. Using a tire calculator (they are easily found using an internet search), the difference is 2 MPH when driving at 65 MPH. Additionally, the Terrains with 19"wheels have higher rear end gearing (If you review the terrains speciifcations it will show the difference) resulting in better acceration with the 19" wheels.

 

[Roesterman]

Tire size comparison.

Website http://www.1010tires.com/TireSizeCalculator.asp?action=submit

 

[stylegal]

Had a monthly status report on email from Onstar for my Terrain SLT-2 indicating two of the tires were below spec in pressure reading. Went through the process of adjusting the tire pressure to find out that when I'm sitting behind the wheel, in the driver's seat, and looking at the tire pressure display on the console, the tires in the schematic at the top are actually the rear tires and the bottom ones in the schermatic are actually the front tires. This seems very upside down to me. ???
My Explorers were never upside down, like this.
Should I be standing on my head when I check them, too ???
Is mine the only Terrain like this or is it a GM thing?
Any comments are appreciated.
Thanks.
Stylegal

Love the wheels but will have to practice standing on my head

 

[GARYD]

Stylegal, Sounds backasswards to me too.

Sactruck, now that you've rode on both sizes, which do you think gives a softer ride or does it make any difference?
I asked this question on another post because I want a softer ride and all the articles said the bigger wheels/tires are harsher.

 

[noncon]

Additionally, the Terrains with 19"wheels have higher rear end gearing (If you review the terrains speciifcations it will show the difference) resulting in better acceration with the 19" wheels.

Larger wheel/tire results in lower acceleration, unless you compensate for this with a change in the driveline ratio, which is mostly likely the reason for the gear ratio change. It just brings the acceleration back to what the vehicle with 18" tires have. Although larger wheel/tire will have a slightly higher top speed. Either way the difference in both is tiny, the difference is probably measured in tenths.

KJ

 

[sactruck]

Check my post from today in the wheel thread. Both the 18" and 19" tires have the same sidewall so the ride should be the same (My seat of the pants did not see much difference). My biggest consideration would be the cost of the optional wheels and the actual tires (The 18 " tires are Michelins made in the USA/ The 19" tires are Hancooks made in China).

 

[gearhead]

Stylegal, Sounds backasswards to me too.

Sactruck, now that you've rode on both sizes, which do you think gives a softer ride or does it make any difference?
I asked this question on another post because I want a softer ride and all the articles said the bigger wheels/tires are harsher.[/color]

I don't think it's so much the wheel/tire size, GARYD, but the tire profile.
If you go with a higher profile tire on the same size rim, you'll generally get a softer ride since there's more air and rubber.

{EDIT}Noticed sactruck posted same time as I was, thanks for the feedback sactruck! {/EDIT}