Measure both pipe ends
Compare the larger and smaller pipe dimensions with the reducer size. Confirm inside and outside diameters at each connection.
Semi-Truck Exhaust Reducers & Rain Caps
Compare 6-to-5-inch and 7-to-5-inch exhaust reducers, plus stainless rain caps for 5-, 6-, 7- and 8-inch straight stacks. Match the pipe dimensions and connection style to your current exhaust setup.
Choose aluminized or chrome reducer options where listed, and check the I.D./O.D. selection at both ends. For a rain cap, confirm the straight stack diameter and room for the flap to move before ordering.
US$33.29
US$53.99
US$63.99
Choosing Exhaust Reducers & Straight-Stack Rain Caps
Choose the connection & finish
Select the listed I.D./O.D. combination for your setup. Compare aluminized and chrome finishes where available, then check the joint’s clamp requirements.
Match the rain cap to the stack
Choose the cap listed for your straight stack diameter. Check mounting clearance and leave enough room for the flap to open freely.
Exhaust Reducer & Rain Cap FAQs
What exhaust reducer sizes are available?
The current range includes an aluminized 6-to-5-inch reducer and chrome 6-to-5-inch and 7-to-5-inch reducers. Check the product page for the exact connection style and availability.
What do I.D. and O.D. mean on an exhaust reducer?
I.D. means inside diameter; O.D. means outside diameter. The reducer style identifies these measurements at each end. Compare both ends with the pipes you are joining, rather than choosing only by the nominal 6-to-5-inch or 7-to-5-inch size.
Which reducer connection styles can I choose?
Reducer listings offer I.D. to I.D., I.D. to O.D., O.D. to I.D. and O.D. to O.D. options. Select the style that matches the mating pipe measurements and your intended joint arrangement. Confirm the exact option on the product page before adding it to the cart.
How do aluminized and chrome exhaust reducers differ?
The aluminized 6-to-5-inch listing specifies aluminized steel. The chrome reducer listings offer a chrome-plated finish. Choose the listed size and end connections first, then compare the finish with the surrounding exhaust components.
What rain cap size do I need?
This category lists stainless rain caps for 5-, 6-, 7- and 8-inch diameter straight stacks. Measure the stack and choose the cap listed for that diameter. Check its mounting arrangement and flap clearance on your truck.
How does an exhaust rain cap work?
The checked 5-inch rain cap has a counter-balanced flap designed to open with exhaust pressure and close when the engine is off, helping keep rain and debris out of the stack opening. Check the individual listing and make sure the flap can move freely after installation.
Can I use these rain caps on curved or mitred exhaust stacks?
These products are listed for straight stacks. Do not assume they fit a curved, bull or mitred tip. Confirm the opening shape and mounting requirements before choosing a cap for a different stack style.
Are reducers and rain caps sold as pairs or with extra hardware?
The checked aluminized reducer, chrome 7-to-5-inch reducer and 5-inch rain cap listings each describe one item. Review the exact listing for quantity and included hardware; order separate clamps or other components only after confirming the joint requirements.