Madmax1993
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Sorry I missed this until just now when I came to post an update, but that's very helpful vis-à-vis the reasoning behind brands settling on 120/70 and Suzuki choosing the wider 6.00 rim on the rear.Hi,
Motorcycle tyres has been my job for 35 years and I hope you don't mind if I give you a few facts. You don't have to follow them, it's your bike after all, but please read and understand the results of what you're hoping to do.
For most regular street bikes, over the years the front tyre size has narrowed down to one size: 120/70-17. On a 3.5" rim (your size) it offers the best balance of performance and comfort on the road.
35 years ago a couple of manufacturers experimented with 130/60-17 front size but it gave no advantages and a few disadvantages and was dropped within a handful of years.
Rear tyre size has changed a bit over the years with sizes growing from 180/55-17 at the end of the '80s, to 190/50-17 to 190/55-17 to today's 200/55-17. But the size fitted to a bike is dependent on the rear wheel width.
Your SRAD has a 6.00" wheel and in its day the 190/50-17 was the optimum tyre size for this rim width.
It is permissible to fit a 180/55-17 tyre on a 6.00" rim but the tyre's profile will be flattened. This is to be expected as the 180/55-17 was designed for a 5.5" rim. By fitting it on a 6.00" rim you are pulling the beads farther apart than is optimum and the result is a flattened profile.
In day-to-day riding you might not notice any effect But in sporty riding you will be riding very close to the narrower tyre's tread edge and at bigger lean angles your contact patch will be reduced as you ride off the edge, which I'm sure you'll agree is not desirable.
Even with an optimum sized tyre for any given rim width, under hard cornering you are starting to ride off the tread's edge, but fitting a narrower than optimal size for the rim only exacerbates this.
My advice would always be not to fit a 180/55-17 on an SRAD, stick with the correct 190/50-17 size.
Unfortunately this would eliminate fitting ADV tyres on your bike. Even though many tyre manufacturers approve the fitting of ADV tyre on sports and naked bikes, none of them make ADV tyres in 190/50-17 because no ADV bikes use this size.
It's a shame that Suzuki chose to fit a 6.00" rim of the SRAD because every other GSX-R750 from '92-'95 and '00 until it was dropped a couple of years ago the bikes were fitted with 5.5" rims and 180/55-17 tyres, which would give you any number of ADV tyres to choose from.
if it was my bike I'd choose an entry level street tyre in 120/70-17 and 190/50-17 from one of the main manufacturers, any of which will give more than enough performance for your stated riding style.
For my money, in the entry level sports tyre category Bridgestone's S21 is by far and away the best tyre.
But if you're looking for a more sport-touring, all-round tyre there are several really good entry level tyres. In alphabetical order: Bridgestone BT-023, Metzeler Roadtec Z8, Michelin Pilot Road 4 and Pirelli Angel GT being the standouts.
It's worth pointing out that any of these entry price level tyres will have way more performance than even the best tyres from when the SRAD was launched in 1996.
I hope all of that clears things up rather than complicating matters, but let me know if you have any more questions.
I'll look into those tyre recommendations once it's through the MOT as they are an advisory.
