Let's try this another way, rather going through all these calculations and thorough explanation of what is actual Vs standard mileage methods.....JUST USING MY NUMBERS ONLY IN THIS EXAMPLE ABOVE, enter the $85 WA state renewal fees into I assume you have 2019 Proseries Pro using the Car and Truck Expenses Worksheet and tell me what is Actual Expenses on Ln 22 - SINCE THE $70 PORTION IN THIS CASE IS NOT DEDUCTIBLE as NOTED BELOW, I show $0?  The $15 which is the RTA is considered Property taxes and is EXCLUDED from Ln 18b as stated - and therefore added on Ln 26b, this is why I break it out.  This only relates to WA state.   So do you get on Ln 30 $66?  So then does the $66 then show on Sch C - Ln 9?

See one reference from Turbotax below:

As you correctly identify in your question, in the State of Washington, the only PORTION of your vehicle registration charge that is tax deductible (on Form 1040 Schedule A as an itemized deduction)  -
NOTE THEY ARE REFERRING TO A SCH A DEDUCTION, RATHER THAN SCH C, SAME PRINCIPLE THOUGH.

is the amount shown on your registration statement for the RTA (Regional Transit Authority) tax.  Only residents of King, Pierce, and Snohomish counties, and who live within the Sound Transit District, will have an RTA tax.  If you do not pay RTA taxes, then you DO NOT have a tax deductible portion of vehicle registration fees for Washington vehicles.