Free Shipping with $50 Purchase + Free Returns – Learn More

Screamin' Eagle 10mm Phat Spark Plug Wires

Part Number 31937-99C


Finish / Color: Red



Fat 10mm plug wires add dimension and style to your ride. Screamin' Eagle® boot design and suppression core wires ensure solid connection and maximum voltage transfer between coil and plugs.

  • Red 10mm wire
  • Screamin' Eagle® graphic printed along wire

Fits '99-'17 Dyna® models.

Bike not listed?
Select your year and model to see all the parts that fit your bike.

  • Model
  • Warranty

    1 year limited warranty – Go to for full details
  • Sold in Unit

  • In The Box

    2 spark plug cables
10mm Phat Spark Plug Wires is rated 4.9 out of 5 by 9.
Rated 5 out of 5 by from Perfect Fit Not only are these wires a great price, but they look and perform Perfect. I couldn't be more happy with them.
Date published: 2016-10-12
Rated 5 out of 5 by from Excellent product Honestly got them for the color, which looks great on my Fat Bob. Easy to install and work great.
Date published: 2016-09-19
Rated 5 out of 5 by from Great replacement for OEM wires! Purchased these wires to replace the stock 7mm wires on my 2003 Low Rider. They were very easy to install and look awesome on the ride! As others have said i wish it came with a replacement clip since the old one was too small for the bigger wires. I just used a black zip tie cut to length to secure the wires and it was no problemo!
Date published: 2016-07-16
Rated 5 out of 5 by from 2014 Lowrider FXDL On my 2014 FXDL I wired tied the long wire to under the ignition, and then used a 10mm 2 wire separator down below. Like the look!!
Date published: 2016-01-10
  • y_2018, m_2, d_26, h_20
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.7
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_9
  • loc_en_US, sid_PA-18-3193799B, prod, sort_[SortEntry(order=SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=FEATURED, direction=DESCENDING), SortEntry(order=SUBMISSION_TIME, direction=DESCENDING)]
  • clientName_harleydavidson

Can these plug wires be used on a stock motor with no other screaming eagle upgrades?

Asked by: Jason103
Hello Jason103: I have these pair of plugs on my wish list and checked the fitment for my 2002 FXD Super glide and H-D says they will fit. Also the H-D Company does not charge for returning a item that does not fit, but it has to be in new condition for the credit. Hope it is of some help.....Bob NH
Answered by: Rami
Date published: 2017-12-09

By me changing stock spark plug wire will it change the dyno tune ?

I just had the 1K service done plus I had the Dyno done.
Asked by: sivelez

Are the wires sold in pairs or individual?

Are they sold each or pair?
Asked by: Anarchy83
Hi Anarchy83, The Screamin' Eagle 10mm Phat Spark Plug Wires sold in pairs, they are not sold separately. Thank you for your question.
Answered by: FXS78
Date published: 2015-07-06
  • y_2018, m_2, d_26, h_20CST
  • bvseo_bulk, prod_bvqa, vn_bulk_2.0.7
  • cp_1, bvpage1
  • co_hasquestionsanswers, tq_3
  • loc_en_US, sid_PA-18-3193799B, prod, sort_[SortEntry(order=SUBMISSION_TIME, direction=DESCENDING)]
  • clientName_harleydavidson

Recently Viewed

    Please Hold Your Iron Horses

    You've been sitting idle, so we've ended your session to protect your personal details.

    Continue as guest Sign in
    Online Exclusives

    You’ve been sitting idle, so your session will expire in

    Would you like to remain signed in and continue shopping?

    Yes, keep me signed in No, sign me out

    Prices listed are generally the Manufacturer's Suggested Retail Price (MSRP), excluding taxes and shipping. Prices at local dealerships may vary. All online orders will be fulfilled and shipped by
    Harley-Davidson Motor Company as the agent for the Selling Dealer.