This is more ST11 focused but some of the sizes are suitable for the ST13. I did not wite down all these details for other tyres I have used (Conti Road Attacks, Bridgestone BT020, Avon Azaro and Storm, Dunlop Roadsmart, Metzler Z6, Dunlop D205 rear)
ST1100 OEM specs are for standard bikes and pre-96 ABS bike:
110/80 - 18M/C 58 V front
160/70 - 17M/C 73V rear
The 58 and 73 refer to weight rating, the V refers to speed rating. Bias ply tyres are the ones recommended by Honda
ST1100 OEM specs are for 96 and on ABS bikes:
120/70 ZR18 59W front
160/70 ZR 73W rear
The Z refers to speed rating (higher than V) and the R to radial. So from the factory radial tyres were fitted. The front rim on these models was also a bit wider to use the wider front tyre.
Now to the specifications and construction of some tyres I have lying around. While radial tyres are not specified by Honda for standard bikes, many have used them successfully. Bias tyres seem to last longer, but they are impossible to come by in Australia.
Avon Storm Ultra II
Front 110/80 ZR18 58W Tread 2xrayon and 2xaramid plies, sidewall 2xrayon plies
Rear 160/70 R17 79V Tread 2xrayon and 1xsteel plies, sidewall 2x rayon plies
Subjective comment: feel really good in all conditions. Ride bumps well, great in the wet, good tyre life for me (13,000kms a pair). Rear tyre is extra reinforced above OEM spec as it also goes on the BMW LT1200 BMW. Earlier Avons were also good, but the original Storm only got 10,000kms. Cost $520 bought and fitted locally.
Michelin Pilot Road 2
Front 110/80 ZR17 58W tread 2xpolymide and 1xaramid, sidewall 2xpolymide
Front 120/70 ZR1 59W tread 2xpolymide and 1xaramid, sidewall 2xpolymide
Rear 170/60 ZR17 72W tread 2xpolymide and 1xaramide, sidewall 2xpolymide
Subjective comment: haven't used these myself but they feel a lot softer in the carcass than other tyres, so may ride more comfortably. Riders I know get 13,000kms plus a set out of these. I have a set in the garage to use sometime. I have a set of 110/80 front and 170/60 rear that owe me $300 from the US. Yet to use them, so don't know whether feeling so soft in the carcass will result in less lifefor me. Locally cost over $500 fitted
Shinko Verge
Front 120/70 ZR18 59W tread 3xnylon and 2xaramid, sidewall 2xnylon
Rear 170/60 ZR17 72W tread 3xpolymide and 1xsteel, sidewall 2xpolymide
Subjective comment: Great tyres compared to all the others I have used. Good in all conditions including the wet. Last well to as over 13,000kms on the set. May get 15,000kms but I will have to change before a few longer trips. As you would expect from the construction they feel stiffer on the road, so not as comfortable over bumps. They have a sportier feel which I do not mind. Cost me $220 a pair from the US, I fit them
