Re: Upgrading to a larger tire

From: Bob Tom (tigers@bserv.com)
Date: Sun Jan 16 2000 - 07:56:22 EST


At 12:36 AM 1/16/00 -0500, you wrote:
>I own a 1997 Dakota Sport 4x2 with P215/75R15 tires. I would like to a
>P235/75R15 tire but was told by my Dodge dealer not to do it because it
>would affect the computer in the vehicle and the ABS brakes and overall
>performance of the truck. If anyone has upgraded their tires to a larger size
>and experienced any problems with the above let me know. Thank you. (Rick)

Hey, Rick

I switched from the 215-75s to 235-75s in Mar. '98 and I've had no problems
whatsoever. I also changed the speedo pinion gear to have the speedometer/
odometer gauges read accurately. If your gear ratio is 3.55:1, the part
number for the speedo gear for the 235-75s is 520067633, last 2 digits
indicating the number of teeth of the pinion gear.

I can't say how the swap affects the computer. If it does, it's not
noticeable. The rear ABS work fine. Driveability changes would be similar
on any car that has gone through a swap to taller tires. Any cruise rpm would
be equivalent to a vehicle with about a 3.50:1 gear ratio. The swap affects
acceleration in that you will have changed the number of tire revolutions
per mile.
In this case, you'll move a bit further with each revolution of the tires.
This
is the main reason why taller tires seem to act like higher gears
(numerically lower).
You'll may experience a small increase in gas mileage, assuming you don't
change your driving habits.

Hope this helps.

Bob. Southern Ontario, Canada.
'97 Dakota CC Sport, FR, 5.2L, 3.55 SG, auto.



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