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-   -   RPM change with change of tires??? (http://www.wranglerforum.com/f210/rpm-change-with-change-of-tires-66182.html)

AdrenalineJunky45 10-22-2010 09:45 AM

RPM change with change of tires???
 
I just recently went from 31s to 33s. in city and off road all was cool but today was the first day i had taken it on the highway to work. It is and 05 TJ Sport, Automatic. I throw o/d off untill i hit about 60-65 mph and then it usually hits around 2100 rpm's, although today it ran high,3100 rpm's, the throttle also increases slowly until a certain point to where it jumps real high. would someone please explain? :confused:

jgorm 10-22-2010 10:00 AM

Sounds like it didn't kick into OD. Remember that with bigger tires your shift points will be higher (mph) than before. (and your speedo will read slower than you are actually going)

AdrenalineJunky45 10-22-2010 10:23 AM

is it common for od to somtimes not kick in?

jasonwrangler 10-22-2010 10:51 AM

when its cold also when throttle opening is bigger than a certain point
in your case bigger tires are making your engine work harder, time to gear down.

TJeepman 10-22-2010 11:44 AM

Additional load on your engine with the bigger tires so the transmission goes down a gear to compensate. To be expected though. Click here for a tire size calculator that will tell you how much your speedometer/odometer will be off.

AdrenalineJunky45 10-22-2010 03:03 PM

okay, cool so ill be kay then right? in a month im puttin on my lift and then after that im gonna save up to regear it, i should be fine till then right?

AzTJ 10-23-2010 12:24 AM

Quote:

Originally Posted by AdrenalineJunky45 (Post 835272)
okay, cool so ill be kay then right? in a month im puttin on my lift and then after that im gonna save up to regear it, i should be fine till then right?

So long as you don't mind the lack of extra power and terrible gas mileage... yeah, you'll survive. :wavey:

jgorm 10-23-2010 10:25 AM

Quote:

Originally Posted by AzTJ (Post 836066)
So long as you don't mind the lack of extra power and terrible gas mileage... yeah, you'll survive. :wavey:

Its not that bad;) The lack of power is really only in 1st and 5th gear. You can use the other gears to "simulate" regearing. I got the same mpg with 33s as 31s once i accounted for the difference in what the odometer said and how far i really went. If you don't do that, you will think you are getting horrible gas mileage!


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