1972 bmw r75/5 'die hexe'

The specs on early '70's airheads are 3.25x19 front and 4.00x18 rear. Most manufacturers however no longer use "english" tire sizes and have been replaced by approx metric sizes. Michelin, Metzeler, Continental and Avon however are some of the few manufacturers that still make the exact tire sizes that originally were to spec.

After a bit of investigation, I went with the Avon Roadridders from AMT in part becuase of the reviews, quick services and lowest prices I could find:

AVON ROADRIDER 4.00-18 M/C 64V, REAR AVON ROADRIDER 4.00-18 M/C 64V, REAR $116.29
AVON ROADRIDER 3.25-19 M/C 54V, FRONT/REAR AVON ROADRIDER 3.25-19 M/C 54V, FRONT/REAR $96.06
MICHELIN TUBE 3.25/3.50-19, 90/90-19 TO 120/60-19, CTL MTL VLV - Price: $19.71
MICHELIN TUBE 4.00/4.50-18, 100/90-18 TO 140/80-18, CTR MTL VLV - Price: $27.95

Avon Roadrider tire specifications

The following specs are obtained from Avon's site

BMW, Model: R75, /5/6/7 1970-1978 - Front Pressure: 2.2 bar (32psi), Rear Pressure: 2.5 bar (36psi)

Technical Specifications
Tire	Tire			Service		Rec	Rim	OW	OW	OD	OD	Depth	Revs	Revs
Model	Position	Sku	Tire Size	Index	Sidewall	Rim	min-max	mm	Inches	mm	Inches	mm	per km	per Mile
Roadrider	Universal	2267513	3.25-19	54V	bw	MT2.15	1.85 - 2.50	98	3.9	664	26.1	5.0	499	797.9
Roadrider	Rear	2276813	4.00-18	64V	bw	MT2.50	2.15 - 3.00	116	4.6	671	26.4	7.5	493	789.6