• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Explorer ST Forum and Explorer ST community dedicated to Explorer ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Explorer ST Forum today!

Temp spare tire diameter vs. OE size

Jniel

New Member
Messages
1
Reactions
0
Location
Belvidere, IL
#1
The Explorer ST T165/70D18 temporary spare has a 27.1" diameter vs the 31.0" diameter of the 255/55R20 OE tires (or the 30.8" diameter for the 275/45R21 size). That's a pretty big difference in rev/mile. Does anyone know if the electronics of the drivetrain cancel out any worry about what that difference does to the differential?
 

Izero

New Member
Messages
7
Reactions
1
Location
New Jersey
#2
This is what the manual says:


Dissimilar Spare Wheel and Tire Assembly Information
WARNING: Failure to follow these guidelines could result in an increased risk of loss of vehicle control, injury or death.

If you have a dissimilar spare wheel and tire, then it is intended for temporary use only. This means that if you need to use it, you should replace it as soon as possible with a road wheel and tire assembly that is the same size and type as the road tires and wheels that were originally provided by us. If the dissimilar spare tire or wheel is damaged, you should replace it rather than repair it.
A dissimilar spare wheel and tire assembly is defined as a spare wheel and tire assembly that is different in brand, size or appearance from the road tires and wheels and can be one of three types:
1. T-type mini-spare: This spare tire begins with the letter T for tire size and may have Temporary Use Only molded in the sidewall.
2. Full-size dissimilar spare with label on wheel: This spare tire has a label on the wheel that states: THIS WHEEL AND TIRE ASSEMBLY FOR TEMPORARY USE ONLY.
When driving with one of the dissimilar spare tires listed above, do not:
  • Exceed 50 mph (80 km/h).
  • Load the vehicle beyond maximum vehicle load rating listed on the Safety Compliance Label.
  • Tow a trailer.
  • Use snow chains on the end of the vehicle with the dissimilar spare tire.
  • Use more than one dissimilar spare tire at a time.
  • Use commercial car washing equipment.
  • Try to repair the dissimilar spare tire.
Use of one of the dissimilar spare tires listed above at any one wheel location can lead to impairment of the following:
  • Handling, stability and braking performance.
  • Comfort and noise.
  • Ground clearance and parking at curbs.
  • Winter weather driving capability.
  • Wet weather driving capability.
  • Four-wheel driving capability.
3. Full-size dissimilar spare without label on wheel.
When driving with the full-size dissimilar spare wheel and tire assembly, do not:
  • Exceed 70 mph (113 km/h).
  • Use more than one dissimilar spare wheel and tire assembly at a time.
  • Use commercial car washing equipment.
  • Use snow chains on the end of the vehicle with the dissimilar spare wheel and tire assembly.
The usage of a full-size dissimilar spare wheel and tire assembly can lead to impairment of the following:
  • Handling, stability and braking performance.
  • Comfort and noise.
  • Ground clearance and parking at curbs.
  • Winter weather driving capability.
  • Wet weather driving capability.
  • Four-wheel driving capability.
When driving with the full-size dissimilar spare wheel and tire assembly additional caution should be given to:
  • Towing a trailer.
  • Driving vehicles equipped with a camper body.
  • Driving vehicles with a load on the cargo rack.
Drive cautiously when using a full-size dissimilar spare wheel and tire assembly and seek service as soon as possible.
And the more important one:

Operating Four-Wheel Drive (4WD) Vehicles With Spare Tires Do not use a different size spare tire other than the tire provided. If the mini-spare tire is installed, the 4WD system will disable and enter rear-wheel drive only mode to protect driveline components. Some limited 4WD traction could be provided if the mini-spare is installed on one of the front wheels. If you are in driving conditions where limited 4WD traction is needed while the mini-spare is installed, it is recommended the mini-spare be installed on the front axle. See Information Messages (page 120).
 

BullMoose

New Member
Messages
13
Reactions
10
Location
Anderson, SC, USA
#3
I read this when I read the manual after taking delivery of my vehicle. So many things to learn, reading the manual is a must.
 


Top