I don’t get over to that side of El Paso too often. As soon as I-10 hits New Mexico, it drops to 75 all the way to the AZ border.
The 85mph speed limit begins at the Kerr County line about 15 miles east of Kerrville and ends at the El Paso County 460 miles later, and about 35 miles east of El Paso itself.
And it’s also 85mph from where I-20 splits off from I-10 for about 40 miles almost to Odessa.