Post Driver Size Guide: Choose the Right Size (and Adapters)
Driving fence posts shouldn't be a guessing game. Whether you are a rancher fencing livestock or a contractor building a vineyard, choosing the correct pneumatic post driver size is critical for safety, efficiency, and preventing damage to your posts.
If you buy a driver that is too small, your post won't fit. If it's too big without the right adapter, you risk mushrooming the top of the post or damaging the driver itself.
Use this post driver size guide to match your post’s Outside Diameter (OD) to the correct Man Saver Post Driver model.
What Size Post Driver Do I Need?
To select the correct Rohrer Man Saver driver, follow these three steps:
-
Measure the Outside Diameter (OD) of your fence post. Do not rely on "nominal" trade sizes (e.g., a "2-inch pipe" often has an OD of 2.375").
-
Match the OD to a driver model. The driver’s Max OD must be equal to or larger than your post's actual diameter.
-
Check for Adapters. If your post is significantly smaller than the driver’s Max OD, or if you are driving T-posts with a round driver, you must use an adapter or sleeve to ensure a tight, efficient drive.
Shop by Size
[Shop 2" Max OD] [Shop 2-3/8" Max OD] [Shop 2-7/8" Max OD] [Shop 3-1/2" Max OD]
Rohrer Post Driver Size Chart (Max OD)
Find your post type below to see which model provides the best fit and performance.
|
Your Post Type / Size
|
Measured OD / Diagonal
|
Recommended Model
|
Adapter/Sleeve Needed?
|
|
Standard T-Post
|
N/A
|
98-E T-Post Driver
|
No (Native Fit)
|
|
1.5" Round (Timeless)
|
1.5"
|
98-E T-Post Driver
|
No (Native Fit)
|
|
Small Round
|
Up to 7/8"
|
98-E T-Post Driver
|
Yes (7/8" Sleeve)
|
|
Small Round
|
Up to 1-1/4"
|
98-E T-Post Driver
|
Yes (1-1/4" Sleeve)
|
|
2" Round Pipe
|
~1.90" - 2.00"
|
90-R Post Driver
|
No
|
|
2-3/8" Round Pipe
|
~2.375"
|
91-R Post Driver
|
No
|
|
2-7/8" Round Pipe
|
~2.875"
|
93-R Post Driver
|
No
|
|
3-1/2" Round Pipe
|
~3.50"
|
95-R Post Driver
|
No
|
|
T-Post (Alt Option)
|
N/A
|
91-R, 93-R, or 95-R
|
Yes (Model-Specific Adapter)
|
Model Specifications & Air Requirements
Different sizes require different air capacities. Ensure your compressor matches these specs:
-
90-R (2" Max OD): 2.5 CFM @ 70 PSI (Max 70 PSI). Delivers ~70–75 strokes/min.
-
91-R (2-3/8" Max OD): 3.5 CFM @ 80 PSI (Max 80 PSI). Delivers ~70–75 strokes/min.
-
93-R (2-7/8" Max OD): 3.5 CFM @ 90 PSI (Max 90 PSI). Delivers ~60–70 strokes/min.
-
95-R (3-1/2" Max OD): 3.5 CFM @ 90 PSI (Max 90 PSI). Delivers ~50–60 strokes/min.
-
98-E (T-Post): 2.5 CFM @ 70 PSI. Delivers ~80–85 strokes/min.
[Talk to Tech Support for Sizing Help]
How to Measure Your Post Correctly (OD vs. Nominal)
One of the most common mistakes in buying a post driver is confusing "Nominal Pipe Size" with "Outside Diameter" (OD).
Measurement Steps
-
Use Calipers: This is the most accurate method. Clamp the calipers around the widest part of the post.
-
Tape Measure: If you don't have calipers, wrap a tape measure around the post to get the circumference. Divide that number by 3.14 (π) to get the diameter.
-
Check for Coatings: If you are using coated pipe or reused pipe with dents/weld splatter, measure the widest point. The driver needs clearance to slide freely.
Pro Tip: If your measurement is within 1/16" of the driver's Max OD, we recommend sizing up and using an adapter to prevent jamming.
When You Need Adapters vs. Sleeves
Rohrer Manufacturing offers two types of accessories to modify the size of your driver: Adapters and Sleeves.
1. Driving T-Posts with Round Drivers (Adapters)
If you already own a larger round driver (like the 93-R) but occasionally need to drive T-posts, you don't necessarily need to buy a separate 98-E driver. You can buy a T-post adapter that slides into your round driver.
2. Driving Smaller Round Posts (Sleeves)
If you have the 98-E T-Post driver, you can convert it to drive small round posts (like electric fence rods or fiberglass posts) using a sleeve.
3. Sizing Down (Round Adapters)
If you own a large driver (e.g., 95-R) but need to drive a batch of 2" pipe, using the bare driver allows too much "slop," which makes it hard to keep the post straight. Use a reducing adapter to snug up the fit.
[Browse All Adapters & Sleeves]
Common Sizing Mistakes
-
Buying "Exact Fit" with zero tolerance: If your post is exactly 2.375" and the driver opening is exactly 2.375", any paint, rust, or bend in the post will cause the driver to bind. Always ensure the driver Max OD is slightly larger than your post.
-
Exceeding Max OD: Never try to force a post into a driver. If it doesn't slide in easily, do not hammer it on. You will damage the lower housing of the tool.
-
Using the wrong T-post solution: Remember, the 98-E is a dedicated T-post driver. The 90-R, 91-R, 93-R, and 95-R are round drivers that can drive T-posts only if equipped with the correct adapter.
Frequently Asked Questions (FAQ)
What does “Max OD” mean on Rohrer post drivers?
Max OD stands for Maximum Outside Diameter. It represents the largest physical opening of the driver. Your post's outside diameter must be smaller than this number for the post to fit inside the barrel.
Which Rohrer driver do I need for a 2-3/8" OD round post?
For a 2-3/8" OD post (often referred to as 2" schedule 40 pipe), you need the 91-R Post Driver. The 90-R (2" Max OD) will be too small.
Can I use adapters to drive T-posts with 91-R / 93-R / 95-R?
Yes. We sell specific T-post adapters for the 91-R, 93-R, and 95-R models. This allows you to use one heavy-duty driver for both your corner posts (round) and line posts (T-posts).
What’s the difference between 93-R and 95-R besides size?
Aside from the size capacity (2-7/8" vs 3-1/2"), the stroke speed differs. The 93-R operates at 60–70 strokes/minute, while the larger 95-R hits harder but slightly slower at 50–60 strokes/minute. Both require 3.5 CFM at 90 PSI.
How do I size for square posts?
To drive square posts, you must measure the diagonal (corner to corner), not the flat width. This diagonal measurement must be smaller than the driver’s Max OD. We also offer adapters specifically for square tubing.
Need Personal Sizing Advice? We from Rohrer Manufacturing can help you in Prineville, OR.
We are based in Prineville, Oregon, and we know our tools inside and out. If you have a unique post shape or difficult soil conditions, give us a call before you order.
When you select the correct Man Saver Post Driver, you aren't just buying a tool; you are buying speed. You are removing the back-breaking labor of hand-driving or the danger of heavy hydraulic units.
Matching the driver to the post allows the pneumatic engine to work at peak efficiency, delivering up to 85 strokes per minute exactly where it counts.
Ready to get the right fit? Rohrer Manufacturing has established itself as the leader in pneumatic drivers, serving fence contractors and farmers across the globe from our headquarters in Prineville, Oregon. Our team personally reviews sizing questions to ensure you get the right adapter for your specific situation. Contact Us and/or Visit Us in Prineville, OR.
Orders typically ship M-F. See product pages for specific shipping cutoffs.
Post Driver Size Guide: Choose the Right Size (and Adapters)
Post Driver Size Guide: Choose the Right Size (and Adapters)
Driving fence posts shouldn't be a guessing game. Whether you are a rancher fencing livestock or a contractor building a vineyard, choosing the correct pneumatic post driver size is critical for safety, efficiency, and preventing damage to your posts.
If you buy a driver that is too small, your post won't fit. If it's too big without the right adapter, you risk mushrooming the top of the post or damaging the driver itself.
Use this post driver size guide to match your post’s Outside Diameter (OD) to the correct Man Saver Post Driver model.
What Size Post Driver Do I Need?
To select the correct Rohrer Man Saver driver, follow these three steps:
Measure the Outside Diameter (OD) of your fence post. Do not rely on "nominal" trade sizes (e.g., a "2-inch pipe" often has an OD of 2.375").
Match the OD to a driver model. The driver’s Max OD must be equal to or larger than your post's actual diameter.
Check for Adapters. If your post is significantly smaller than the driver’s Max OD, or if you are driving T-posts with a round driver, you must use an adapter or sleeve to ensure a tight, efficient drive.
Shop by Size
[Shop 2" Max OD] [Shop 2-3/8" Max OD] [Shop 2-7/8" Max OD] [Shop 3-1/2" Max OD]
Rohrer Post Driver Size Chart (Max OD)
Find your post type below to see which model provides the best fit and performance.
Your Post Type / Size
Measured OD / Diagonal
Recommended Model
Adapter/Sleeve Needed?
Standard T-Post
N/A
98-E T-Post Driver
No (Native Fit)
1.5" Round (Timeless)
1.5"
98-E T-Post Driver
No (Native Fit)
Small Round
Up to 7/8"
98-E T-Post Driver
Yes (7/8" Sleeve)
Small Round
Up to 1-1/4"
98-E T-Post Driver
Yes (1-1/4" Sleeve)
2" Round Pipe
~1.90" - 2.00"
90-R Post Driver
No
2-3/8" Round Pipe
~2.375"
91-R Post Driver
No
2-7/8" Round Pipe
~2.875"
93-R Post Driver
No
3-1/2" Round Pipe
~3.50"
95-R Post Driver
No
T-Post (Alt Option)
N/A
91-R, 93-R, or 95-R
Yes (Model-Specific Adapter)
Model Specifications & Air Requirements
Different sizes require different air capacities. Ensure your compressor matches these specs:
90-R (2" Max OD): 2.5 CFM @ 70 PSI (Max 70 PSI). Delivers ~70–75 strokes/min.
91-R (2-3/8" Max OD): 3.5 CFM @ 80 PSI (Max 80 PSI). Delivers ~70–75 strokes/min.
93-R (2-7/8" Max OD): 3.5 CFM @ 90 PSI (Max 90 PSI). Delivers ~60–70 strokes/min.
95-R (3-1/2" Max OD): 3.5 CFM @ 90 PSI (Max 90 PSI). Delivers ~50–60 strokes/min.
98-E (T-Post): 2.5 CFM @ 70 PSI. Delivers ~80–85 strokes/min.
[Talk to Tech Support for Sizing Help]
How to Measure Your Post Correctly (OD vs. Nominal)
One of the most common mistakes in buying a post driver is confusing "Nominal Pipe Size" with "Outside Diameter" (OD).
Nominal Size is a trade term. A "2-inch schedule 40 pipe" actually measures 2.375 inches across. If you buy a 2" driver (90-R) for this pipe, it will not fit. You need the 2-3/8" driver (91-R).
Measurement Steps
Use Calipers: This is the most accurate method. Clamp the calipers around the widest part of the post.
Tape Measure: If you don't have calipers, wrap a tape measure around the post to get the circumference. Divide that number by 3.14 (π) to get the diameter.
Check for Coatings: If you are using coated pipe or reused pipe with dents/weld splatter, measure the widest point. The driver needs clearance to slide freely.
Pro Tip: If your measurement is within 1/16" of the driver's Max OD, we recommend sizing up and using an adapter to prevent jamming.
When You Need Adapters vs. Sleeves
Rohrer Manufacturing offers two types of accessories to modify the size of your driver: Adapters and Sleeves.
1. Driving T-Posts with Round Drivers (Adapters)
If you already own a larger round driver (like the 93-R) but occasionally need to drive T-posts, you don't necessarily need to buy a separate 98-E driver. You can buy a T-post adapter that slides into your round driver.
2. Driving Smaller Round Posts (Sleeves)
If you have the 98-E T-Post driver, you can convert it to drive small round posts (like electric fence rods or fiberglass posts) using a sleeve.
3. Sizing Down (Round Adapters)
If you own a large driver (e.g., 95-R) but need to drive a batch of 2" pipe, using the bare driver allows too much "slop," which makes it hard to keep the post straight. Use a reducing adapter to snug up the fit.
[Browse All Adapters & Sleeves]
Common Sizing Mistakes
Buying "Exact Fit" with zero tolerance: If your post is exactly 2.375" and the driver opening is exactly 2.375", any paint, rust, or bend in the post will cause the driver to bind. Always ensure the driver Max OD is slightly larger than your post.
Exceeding Max OD: Never try to force a post into a driver. If it doesn't slide in easily, do not hammer it on. You will damage the lower housing of the tool.
Using the wrong T-post solution: Remember, the 98-E is a dedicated T-post driver. The 90-R, 91-R, 93-R, and 95-R are round drivers that can drive T-posts only if equipped with the correct adapter.
Frequently Asked Questions (FAQ)
What does “Max OD” mean on Rohrer post drivers?
Max OD stands for Maximum Outside Diameter. It represents the largest physical opening of the driver. Your post's outside diameter must be smaller than this number for the post to fit inside the barrel.
Which Rohrer driver do I need for a 2-3/8" OD round post?
For a 2-3/8" OD post (often referred to as 2" schedule 40 pipe), you need the 91-R Post Driver. The 90-R (2" Max OD) will be too small.
Can I use adapters to drive T-posts with 91-R / 93-R / 95-R?
Yes. We sell specific T-post adapters for the 91-R, 93-R, and 95-R models. This allows you to use one heavy-duty driver for both your corner posts (round) and line posts (T-posts).
What’s the difference between 93-R and 95-R besides size?
Aside from the size capacity (2-7/8" vs 3-1/2"), the stroke speed differs. The 93-R operates at 60–70 strokes/minute, while the larger 95-R hits harder but slightly slower at 50–60 strokes/minute. Both require 3.5 CFM at 90 PSI.
How do I size for square posts?
To drive square posts, you must measure the diagonal (corner to corner), not the flat width. This diagonal measurement must be smaller than the driver’s Max OD. We also offer adapters specifically for square tubing.
Need Personal Sizing Advice? We from Rohrer Manufacturing can help you in Prineville, OR.
We are based in Prineville, Oregon, and we know our tools inside and out. If you have a unique post shape or difficult soil conditions, give us a call before you order.
When you select the correct Man Saver Post Driver, you aren't just buying a tool; you are buying speed. You are removing the back-breaking labor of hand-driving or the danger of heavy hydraulic units.
Matching the driver to the post allows the pneumatic engine to work at peak efficiency, delivering up to 85 strokes per minute exactly where it counts.
Ready to get the right fit? Rohrer Manufacturing has established itself as the leader in pneumatic drivers, serving fence contractors and farmers across the globe from our headquarters in Prineville, Oregon. Our team personally reviews sizing questions to ensure you get the right adapter for your specific situation. Contact Us and/or Visit Us in Prineville, OR.
Orders typically ship M-F. See product pages for specific shipping cutoffs.