As above

Ok. I found them a bit draggy (1.95") compared to the conventional semi-slicks I was using, but they're certainly usable. I'm currently trying Panaracer Racer XCs as an on/off road tyre and my experiences are pretty positive to date.

They are not designed for the road so of course they are draggy. IF tarmac is important, get some semi slicks.

I love my SM8's, they are so much better than they look!

Not intending on buying them for road use, but there will be a bit of road required, so wanted to find out what they were like.

I found them more draggy than normal knobblies (Ignitors). There's no central ridge of any form, just rows of horizontally aligned small blocks, this makes for a very draining ride on good road. On hardpack/dust they are fine, because the knobblies sink in leaving a flatter roll profile.

Like Sinatra says they're not designed for the road.

They have a low profile and there's a 'lead in' slope to each row of blocks so they drag a lot less than most. They'll drag more than a slick but less than something like a super tacky Swampthing or other big knobbly you care to mention.

It's pretty subjective but for an off road tyre they're ok on the road (and pretty damn fast off road)

I agree, I had SM8 on my 29er ( thus uniting 2 current threads ) and found them fine on the tarmac for an offroad tyre. I use the 29er for rides from my back door that are a mixture of backroad tarmac, bridleway, Dalby trail centre and moorland singletrack and they were fine in the summer/autumn last year. Subsequently swapped to Panaracer Rampage which have a beefier tread and thus have a slight advantage in the mud of winter and indeed this summer and haven't swapped back yet although I have got a set of 26 inch SM8's going on the other half's bike.

what about semislick on back sm8 up front – some of the charge 4x bikes run this…

A few of us use them on out commute to the trails.

Personally I find Nevegals drag too but are fine on the road to the trail
Have you tried Maxxis TT-bit of a dry tyre only.

Certainly wouldn't say they're draggy at all, they're faster than any other actual usable offroad tyre I've ever used, and not drastically slower than my old road tyres (which have a slight tread, not full slick in the centre). I doubt you'll find anything faster on tarmac that doesn't compromise offroad (I'm really confused by the Maxxis Ignitors comment though, I found them fairly slow on road, a lot slower than the SBs)

It's true they don't have a solid centre roll, but the second row of blocks evens that out a lot- you don't just "cog" along on the middle row. Though like some other tyres they seem to get slower as you up the pressure- they're faster at about 35 than they are at 60, because at lower pressures the load is more spread out while at higher pressures they sit more on the central row, I think.