Low Profile Tyres - on a Dutton?

[James Doulton]

When I went to Castle Combe in August I was rather disappointed with my Legerra's road-holding. I was talking to another guy who had a stripped out Citroen Saxo VTS (he is actually the MOT inspector at the garage I use and did my car just a week before the meeting). His car was not really any faster than me in a straight line but went around the corners completely differently. He reckoned it was just down to tyres - he pointed out that almost everyone else was running Toyo R888's like he was.

According to my calculations (on a big Excel spreadsheet) a small increase in cornering power makes a huge difference to lap times, so it would be well worth improving the cornering, plus it would make me safer on the road if I had a bit more margin.

The trouble is that they don't seem to do them in 195/65 x 14, which is what I am currently using. I have had a look around and it seems that I can keep my existing gearing if I change my wheels and fit either 195/55 x 15's or 205/40 x 17's. I like the idea of the 17 inch wheels, there are quite a few 4 stud ones on fleabay from Focus ST's which would seem suitable.

But there have been comments before that Dutton's don't work well with low profile tyres and so I was wondering why. I can see two potential reasons:

• the first being the camber on the front wheels, mine is somewhere between 2.5 and 3.0 degrees. The camber means that the tyre is distorted more on the inside, by about 9mm, than on the outside. This would presumably matter more with low profile tyres as the side wall is shorter. But then you see kids driving around in lowered cars with MUCH more camber. They look stupid but you'd have thought that they'd correct them if they wore out quickly or handled badly, wouldn't you?
• The second reason that I can think of why low profile tyres might not be so good is that the tyres would probably be a lot less compliant and with a live rear axle that might mean that a bump under one wheel upsets the other one more than it would with a taller tyre. So bumps mid-bend might be more of an issue.

I would be interested to hear other peoples views and experiences with their Duttons.

[Adrian Southgate]

Hi James

I have tried various tyre sizes and settled on 195/60/15 Dunlop fast response, which fill the arches but mean the adjustables need to be wound up a bit. The most comfortable ride was the 185/70/13 (F) and 205/60/13 (R)  combo run at 18-20 PSI.

I've been looking at R888's and A048's for those compomotives or some RS four spokes just for doing trackdays in the future but the expense of a new set is silly. Also a set of Nexen's in 14 inch for the wheels that were on the Sierra.

I've never really pushed the Legerra to it's limits, well never found them on the road anyway. May be an idea to get a few sets of used ones together on rims and try them out on circuit sometime.

[Steve Kerswell]

I think you have 2 different arguments here. 1/ Road work, you have to go for a bit of comfort.2/ Track work, you want the car to handle as best it can. My 2p. worth is: Suspension is far more important then tyres, road work and track work again are so different. Once you get the suspension right then you can play with tyres, but it will always be a compromise on a roadie being tracked. Finally, my friend races a GT6 in classis stuff, he drives my B+ far faster then I can, Why? because he has a lot more track wisdom then me and knows where the limits are, almost :-)) He always says to me, get out there and learn.

[Big Vern]

Sorry Steve but I have to disagree with you there, its all about the tyres everything else is just there to make the tyres work properly or should be its the tyres that contact the road after all.

I have used both 185/70x13 and 205/50x15. The 13's especially in something decently sticky are becoming hard to find now and with the changes to tyre rules for 2016 that'll only get worse. 15's are the way to go as they'll have likely the best range but the stiffer side wall makes the ride harsher, a switch to adjustable dampers should solve that though. My only dislike is the wheels look smaller in the arches which on most duttons are alreadey 'oversize' and tend to make duttons look like they're on stilts.

Decise first what wheel/tyres you want to use then tune the suspension to suit how you want the car to ride, and remember cheap tyres are usually cheap for a reason.....

As for how fast you drive the car thats down to having the confinance to push and see where the limits are - ie know YOUR abilities first!

[Big Vern]

Car originally designed for a size of tyre will tend to work best with that tyre, but tyre technology is always developing - if you don't try other sizes you'll never find out if something new works beter. As for the Caterham and locost formula's most mandate 13's.

As of my visit to the factory last weekend only the base model 'catering vans' had 13's all the other cars they offer appeared to be on 15's

The new tyre regulations are coming in next year. This requires all tyres sold in europe to have better wet grip, lower noise and rolling resistance than is the case currently which many believed was the europeans attempts to stop track day tyres being used on the road (if they don't like them why not just outlaw them for road use)

Toyo have already re-engineered to R888 into the R888r to comply with the forthcoming new rules but they come at a price and they do not currently list any R888r's in 13's

Advan informed me back in June that from 2016 A021r's would still be available for motorsport use but are to be stamped not for road use on the side wall as they will not comply and advan have no intention of re-engineering them to do so. Indeed they stated that there main concern was 15 inch tyres and upward as the volume of sales of tyres of smaller sizes represented a very small part of their european business.

Hankook are in the process of having their track day tyres certified for the new regulations and expect to have road legal trackday tyres in place, but again limited tyre/wheel sizes. No news of Federal yet but expect their RSR's to concentrate on 15's and up.

The larger profile of tyres such as the 13's will always have a more compliant ride due to the softer side wall, but with increased slip angles there is a handling penalty to pay. Lower profile tyres will give a harder ride but will give you the grip you need especially with the right compound and the ride can be improved with adjustable dampers as stated earlier.

[Steve Kerswell]

So I'll stick some sticky rubber on my Sierra and make it go around corners better? 

[Steve Kerswell]

My great grandson has a Tonka type jeep that does that, um, got me thinking now :-))

[Dave Taylor]

I changed tyres this year, stuck with 13" but went down to 165/70 Good Year duragrip, and honestly the have completely changed the handling of my Phaeton. It now goes round bends like it's on rails, and is amazing in the wet. The old tyres where a cheap set and gave plenty of feel, but these Good Years have made it a different car altogether.

[neil parsons]

On my Phaeton I tried

5.5j x 13 ford steelites with 165 and 185 tyres

7j x 16 pug wheels with 205 45 tyres - very harsh ride

6j x 15 citroen c2 steelies with 185 55 15 tyres - this as a good set up

In the end I went back to the ford steelites with 185 70 on back and 165 on front (to give clearance on full lock)

[James Doulton]

Cheers Neil, I was thinking that the Peugeot wheels looked like a good choice because the 206 was fitted with 205/45x16's and 195/50x16's. When I got my car it had 205/60x13's on so I reckon that 205 width should fit if I get the right spacers. I was thinking of the Peugeot wheels because Ford ones seem to carry a premium.

Your Phaeton was probably a bit lighter than my Legerra so the ride might not be as bad (said he, grabbing at straws). Do you remember what tyre pressures you used?

[James Doulton]

Is that 185/60 on the minilites?

[Jim (across the pond) Adamek]

I agree, Low profile tires do not provide the cushion needed on a car as light as a Dutton.

[James Doulton]

Those 215's sound a nightmare. I can remember that 20 years ago tramlining was a problem but you don't tend to hear of it so much nowadays, so I wonder if modern cars suspension is different. I have a Hyundai Coupe with 225/45x17's and it is very well mannered and goes exactly where it is told to.

I wonder what makes our cars so bad for it?