Around 15,000 runners will run the 13.1-mile course and a total of 46 roads across the borough will be shut from 7am.
Throughout the day, routes will be reopened and traffic is expected to return to normal by 2pm.
The A33 will be closed in both directions from 9.30-10.30am but traffic will not be allowed northbound until after 1.25pm once the majority of runners have passed the finish line at the Madejski Stadium.
Among the main routes closed to motorists are Shinfield Road, which will be shut between Whitley Wood and Christchurch Road from 9-11.45am, and London Road, which will shut between Sidmouth Street and Crown Street from 9.30am-midday.
Bath Road will close from 9.30am-1.15pm between Circuit Lane and Coley Avenue, Tilehurst Road is closed from Russell Street to Liebenrood Road, and Oxford Road between West Street and Bedford Road from 9.30am-12.40pm.
Patients with hospital appointments can still get to the Royal Berkshire Hospital from London Road. The Berkshire Independent and Spire Dunedin hospitals can be reached from Bath Road or Berkeley Avenue, and drivers can get to Circle Reading Hospital from Basingstoke Road and Manor Farm Road.
The Smallmead Waste and Recycling Centre and access to the Link Retail Park will open at 2pm and all the town centre car parks will be open as normal, except the Oracle, which is closed until 12.30pm.
Full list of road closures:
A33 (southbound), from Madejski roundabout to Rose Kiln Lane, 9.30-10.30am
A33 (northbound), between Bennet Road and IDR, 9.30am-1.25pm
Bennet Road, 9.30-10.50am
Basingstoke Road, between Imperial Way & Callington Rd, 9.30-10.50am
Island Road, 9.30-1.25pm
Hartland Road, between Basingstoke Rd & Northumberland Ave, 9-11am
Northumberland Avenue, between Hartland Rd & Whitley Wood Rd, 9-11am
Whitley Wood Road, between Whitley Wood Lane and Shinfield Road, 9-11.30am
Shinfield Road, between Whitley Wood Rd and Christchurch Rd, 9-11.45am
Pepper Lane, 9.30-11.45am
Christchurch Road, 9.30-11.50am
Kendrick Road, 9.30am-midday
London Road, between Sidmouth Street and Crown Street, 9.30am-midday
London Street, 9.30am-midday
Mill Lane (north and south), 7am-12.30pm
Duke Street, 9.30am-12.15pm
Thorn Lane, 9.30am-12.15pm
Yield Hall Place, 9.30am-12.15pm
Minster Street, 9.30am-12.15pm
Gun Street, 9.30am-12.15pm
King Street, 9am-12.15pm
King’s Road, between Abbey Street and King Street, 9am-12.30pm
Abbey Square, 9am-12.30pm
Abbots Walk, 9am-12.30pm
The Forbury, 9.30am-12.30pm
Butter Market, 9.30am-12.30pm
High Street, 9.30am-12.30pm
Market Place, 9.30am-12.30pm
Blagrave Steet, between Valpy Street and Friar Street, 9.30am-12.30pm
Valpy Street, 9.30am-12.30pm
Friar Street, between Blagrave Street and West Street, 9.30am-12.30pm
Station Road, 9.30am-12.30pm
West Street, 9.30am-12.30pm
Oxford Road, between West Street and Bedford Road, 9.30am-12.40pm
Russell Street, 9.30am-12.40pm
Tilehurst Road, between Russell Street and Liebenrood Road, 9.30am-12.40pm
Liebenrood Road, 9am-1.30pm
Bath Road, between Circuit Lane and Coley Avenue, 9.30am-1.15pm
Castle Hill, 9.30am-1.15pm
Coley Avenue, between Bath Road and Berkeley Avenue, 9.30am-1.30pm
Berkeley Avenue, between Elgar Road and Shaw Road, 9.30am-1.30pm
Rose Kiln Lane (northbound), between Berkeley Avenue & junction with A33, 9.30am-1.30pm
Longwater Avenue, 7am-2pm
Brook Drive, 7am-2pm
Northern Way, 7am-2pm
Hoops Way, 7am-2pm
Shooters Way, 7am-2pm