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MG Midget and Sprite Technical - 185 Tyres on 5 inch rims

Hi All,

I've read somewhere that even though 185's will fit on 5 inch rims, that isn't really a good option. 175 was the recommended max size you would really want to go to.

I'm looking to do a few track days and think I need more grip, hence wider tyres on my 5inch Minators. I've currently got 165/70 r13 and looking to go to 185/60 r13's.

Any views ?

Cheers
R Bradshaw

As you've asked for views. :)

Grip is from the tyre design and manufacture materials rather than just width so you may gain by keeping the same width but with a better tyre.

Of course whatever width or type of tyres you use if they're not in appropriate contact with the driving surface you won't get the best out of them so you want your suspension (and steering) all in good condition, set up appropriately and operating fully so these are areas you could also check on and perhaps improve with just service and maintenance and/or set up (including appropriate tyre pressures).

It might be that you already have the following and hence your need for vehicle improvement so don't take offence (or agate) - one of the very often forgotten improvements to grip and lots more is driver technique/training.

My personal advice, if your car is mainly for road use, is always to do track days with someone else's car or be very aware that a good track day could be very wearing on the vehicle (tyres, brakes, fuel, etc.) and the driver so be aware of this for the drive home particularly if it's in the vehicle that you've used on the track that day.

More than once I've known of vehicles, for various reasons, that have not been able to be driven home after a track-day - but that's just a very few.
Nigel Atkins

Thanks Nigel,

Good point on the make of tyres, mine are quite old and were probably cheap. I was looking at Yoko's A539's or Falken 914's. But I could stay at my current size and Dunlop Street Responce2's look quite appealing.

As for the car set up, I've spent quite a fair amount of time on this. Frontline front and back, upgraded brakes all round, 5 speed gearbox and a perky 85BHP from the A series. So, not totally track focused, but a good fast road car.

Also, a very good point on driver ability. I've raced karts before hand, endurance mainly, and been ok at this. However, I've never really pushed the midget, so it will be an interesting test of both car and me !

Cheers
Richard
R Bradshaw

What car RWA or SWA. 185/60 13 will go on SWA as a mates used them on his Austin Sprite with Jensen Healey wheels which are 5.5" IIRC. They rubbed the arches even when jacked out a bit until I fitted a Watt's linkage to control the lateral axle movement. If you don't already have extra axle location then a Panhard rod or RTL would benefit the handling.

I have 185/60 13 currently on my frogeye and have done many track days and hillclimbs and never had any issue with noticeable wear as it's a light car. Heavy cars are a different story as on a Castle Combe test day I asked a Lotus Carlton owner about tyre wear and he was expecting to have to replace the set after that days use which was typically 4 goes of 6 laps. IIRC on that same day a BMW got stopped when entering the track as a marshall noticed the tyre worn through to the carcass at the edge from hard cornering.
David Billington

Thanks Dave,

It's a RWA. I've got a Panhard fitted.

Which tyres are you running ?

R Bradshaw

I'm running Avons and have done since the late 1980s on all my cars although the point is moot as I don't know if they even make that size anymore and the car hasn't been on the road for some years so they need to be replaced. I'll look at size and tyre options myself when the car is ready for the road again. I always find they give a good balance between wet and dry grip and not too expensive whichever tyre model it was. I switched to them after finding Firestone 165/70 13 not good especially in the wet and a magazine article Autocar? comparing performance tyres gave them the best rating for a budget performance tyre, that was some years ago.

Just checked the ones I have are Turbospeed CR28 which they don't list in 185/60 13 anymore, they do list a CR28 Sport in 185/60 13 so may have to look into that sometime. The CR28 Sport may be what one of the Avon technicians mentioned I might like to try some years ago as a road legal tyre with an endurance race compound.

http://www.avonmotorsport.com/road-legal/performance/cr28-sport
David Billington

Wow, the Avon's are quite pricey ! I'm looking to get a set for the price of one of those beauties.

Has anyone got experience of the Falken ZE914's or Yokohama A539 or even the Dunlop Streetresponse 2's ?

Cheers
Richard
R Bradshaw

Really you need a track biased tyre. I run Nangkang NS2R in 'street' compound on the track. They hold up way better than a road tyre (my Uniroyal Rain Experts started shedding tread blocks after a morning at Croft). Most road biased tyres will overheat the tread blocks and start coming apart on track, so the sensible thing to do is have a second set of wheels...

For sprints I use a much softer compound (Extreme VR2). These would be a disaster on track, and are not far off a disaster on the road...

I will buy more NS2R when mine are worn out. They stand up well to track day punishment - I have XL ones so the sidewalls are a bit stiffer. They are very poor on the road in the damp though, and the ride is terrible. They can cope with at least 160 miles on a track day without coming to bits though, and the stiffer sidewalls help stop me chewing the outside edges off.

They do them in 175 50 R13 (which is a mini size) and although they will look a bit small, they will help with acceleration.

I run 14 inch wheels to fit over the big brakes. Road tyres are 185 60 on a 14 x 6, track are 185 60 on a 14 x 5.5 and sprint tyres are 185 55 on a 5.5.

160 miles at Croft, and 125 miles on Donington, and the car simply soaks up the abuse. Yes, things will wear out faster, but that's life. I've had a couple of major rear axle leaks, but touch wood everything else has held together. Average of 5 sprints/hillclimbs (13 standing full bore starts in one day on one of them!) and two track days per year, plus a chunk of road use.


Rob Armstrong

Richard,

Certainly more than the 205/60 15 Avon ZV7 set of 4 I bought in 2018 but then that's a more common size these days. I saw some 185/60 13 CR28 Sport at about £118 a corner with VAT and maybe not bad considering the less common size and motorsport compound. If you want sticker shock check out metric tyres, often about 3 times the price of a similar sized inch tyre as a mate found out when he needed some for his performance Citroen. Often people would buy a new set of inch tyres and wheels as it was cheaper than the metric tyres alone. I found that on some bog standard classic Mini tyres, small tyre big price for the size.

I looked up the Falken and Yokohama you mentioned and a good bit cheaper than the Avons shame it's so difficult/expensive to compare unless you can borrow some tyres/wheels.

David Billington

David,
no noticeable tyre wear means your car as well as being light is well set up and not overbraked and probably a your a good driver and well suited to the event.
Nigel Atkins

Richard,
if your tyres are old and possibly had little use then possibly just about any decent new tyres will give improvements.

As David has pointed out looking at figures on paper will only get you so far and expensive is a tyre that doesn't do the job required more than price (to reasonable extent at least). Actual testing on your particular car is the only way to know for certain, what's good on one car may not be so good on another, even if it's the same make and model (plus if a different driver).

Even for road tyres I've had two lots of the same model of Yokos on the same model of car but with slightly different suspension set ups and with the car with the 'lesser' suspension set up the tyres were very good but the 'better' suspension car the same model tyres were poor, about a year between.

I've got a Midget with a modest power increase and FL (the initials mean something different to me) front and rear suspension, (no panhard) type 9 box and very slightly uprated brakes and I'd say only the power increase would be much real advantage for the track on mine (certainly not the driver).

As you probably know often less is more. The FL set up could be good for track after a lot of experimenting with adjusting their settings in combination with the particular tyres, their pressures, suspension bushing, ect., including of course set up of panhard.

Brakes can be overdone, from Karting you'll know every I don't as I only drive on the road and too heavy, unskilled and unmacho for such things as karts and racing but with a lightish but not very powerful car like a Spridget I'd have thought you want to brake as little as possible to carry speed and movement to make up for the lack of power and gearing.

When I bought my wheel and tyre package for my (road only) Midget they came with Yoko a-drive (sadly no longer available) and I realised they were good on the car but not how good until I had to replace them and have found nothing since (in the sizes I want anyway) as good. Tyres are a much undervalued component on a car - except by the likes of race teams and specialists.

EBC brakes by any chance(?), note where I live, and I had a mate that worked for Pagid (before and after the Germans took them over).

David(B), Rob and a few others on here are racey types so you will get more and better advice from them than my very general and often forgotten and mistaken offerings, on track stuff, and just about anything else - other than bad car trade experiences of which I'm extremely qualified. :)
Nigel Atkins

Certainly tyres vary a lot. A mate bought a 2nd hand Peugeot a while back and said it was the only FWD car he had driven that oversteered so I asked what tyres it had on it, he said some well known branded tyres on the front and a no name Chinese on the rear, QED crap grip rear tyres. I had it on the odd other car where driving on the same stretch of wet road the courtesy car with cheap tyres was scary in the wet, mine on the same stretch on Avons no problem. I'm not saying Avon are the best I just like them and they seem consistent in their behaviour for their standard road ranges over more than 30 years and suit me. Most of that time they were made locally but at least the last set were made in Serbia. I've only had one defective tyre and after a simple test I was given a credit note for a replacement by Avon and it was swapped for a new one at the tyre place FOC and sorted the problem, they're less than 10 miles from me in Melksham. I think the technician knew the problem but wouldn't tell me. I do wonder if people buying tyres on price is responsible for the number of small cars off in a ditch in my area, early last year over the course of 2 weeks 3 small cars were in the ditch after a bend which I have never found slippery, the police slippery surface warning sign is still there. Recently just the indication of someone losing it and recovering.

Nigel,

The 2 degree negative camber on the front tele conversion seems to suit pushing the car hard at test days and other speeds events and gives good even wear in my experience but is too much for a wide tyre like 185/60 for regular use on the road as it result in wear of the inner edge. The 165/70 wear was even with road use but I didn't do test or speed events at that time.
David Billington

David,
crap tyres, mismatched tyres and unregulated tyre pressures and condition of tyres - all part of modern drivers and the want for cheapest and no inconvenience of ever checking anything (even for a light on the dash!).

A mate who had his tyres provided and the pick of what he wanted (within reason) always used to go for Avon, again for consistency and in his case grip at speed - he was a rep, then owned his own company and travelled lots of fast miles.

2 degrees! oh the joy of designing and fitting something yourself. IIRC I have 3.5 and 4 degrees from using stacks-of-sh*ts specialist experts. When I scrubbed the edges of off my tyres from charity rides at Rockingham Raceway a couple of years back (and got a chipped windscreen from a Rover 200 as I left on the 20mph road and he came in) Guy thought it would be because of toe-in rather than camber.

Since then I have (mostly) also kept off the rumble strips and don't go to Donnington and the other places we sometimes do.

Notice even when the Marshall waves you on as it's clear I always check for myself.



Nigel Atkins

If you're to the stage that you think you are faster than your tyres, get some Hoosiers and find out what grip is
Or second choice Federals

Looking at that pic of your car Nigel , there's no way that has 4deg camber 0.4 m/be

Biggest problem is tyre pressures- give em heaps, I used to run 40psiF and 36psiR on my midget ,anything less and they'd roll under

William Revit

40psiF & 36psiR - really???
Chris Madge

Thanks all, lots to consider there !

Avon’s sound to be a favourite and their road tyres are reasonably priced. I’ll probably go with these for my first stab at a track day, I’m not going to go too mad. When I do start to push it, I’ll likely invest in another set of rims/ proper track tyres.

As was suggest pressures is vital ( always a closely guarded secret when I was racing karts), as a few psi either way will make a difference. Something to play with whilst waiting for my stint at the track day.

I’ll report back on my experiences after my visit to Goodwood in February.

Cheers all
Richard
R Bradshaw

Yes really Chris--
Don't be afraid to pump em up for a try
Depends on how hard/fast you want to go
William Revit

William

So higher pressures prevent tyres rolling under due to high cornering forces I assume you mean ?

But surely at such high pressures (for a Spridget) this would adversely impact grip, steering, and the suspension effect the tyres provide ?

46 psi at the front is way over the recommended amount.

Chris Madge

"recommended amount" by who---?
Try it
And it's 40 not 46 and 36 rear
Even with 36 in the rear it's boderline too low but best compromise
As i said depends on how fast you want to go
William Revit

By who ? - The Owners manual. Ok I admit tyres have moved on since the manual was published.

I had new tyres fitted by a tyre place and they were inflated to around 36 psi. At that pressure the steering was too light, twitchy and felt vague to me.

Back down to 24 psi and it feels better to drive (again to me)

Chris Madge

Willy,
a photo showing the front of my Midget square on would look more like 35 and 40 degrees.

I remember a previous Aussie poster (was it Rod?) that used to say he had his tyres in the 30s for road use which I think would be quite punishing on the car, driver and and passenger on our typical English roads.

I've no idea about track stuff, never followed the roundy-round stuff, used to go to the local drag strip in late 70s and early 80s and saw 0-300 mph in 4 seconds after that everything looks slow, but I though pressures were reduced when going from road to track use for the light(?) cars (or is that another brain fart of mine?).

Goodwood is about the only track I'd like a drive round and looks like it could be a bit interesting to watch races on, otherwise (heresy I know) I find the roundy-round stuff like watching paint dry, I spent a week one afternoon watching the Silverstone Classic races.

Nearest I got to Goodwood track -




Nigel Atkins

Definitely need higher pressures when hard charging. The actual amount will depend on the combination of vehicle weight, rim width, tyre design, width and aspect ratio.
Even 40 Psi won't cut it for a heavier car on tall aspect ratio tyres, where 50psi or more might be needed to stop the tyre deforming and running partly on the sidewalls. (track day conditions, not road) For lower aspect ratio and lighter cars less pressure is needed.
Paul Walbran

I tried 30 psi in my Yokohama AE01s for my last outing at Harewood to try to stiffen the side-walls and eliminate rubbing.

It was only afterwards that it dawned on my why the rear end was sliding so much on the final bend. I think closer to the normal 24 or 25 would have been better.

Edit: Nearly forgot - earlier in the year there was a square wheel arch Spridget at Loton Park with 175s (might even have been 185s) with no flaring of the wings or rubbing on the wheel arch.

The car did have a panhard rod, but it also had a wire wheel axle - apparently these are slightly shorter than steel wheel axles.
C Mee

Two ways to determine:
First, check whether road contact is extending past the tread area around the corner to the edge of the tyre.
Second involves a lot more testing and is harder to explain, but in summary set up a 10% pressure difference front to rear, with the rear higher than the front. See what the car feels like on your favourite test road, then swap pressures front to rear and try again. The combination that feels least stable has better grip at the front, so that pressure is better.
Paul Walbran

Continuing, as my phone won't let me do long posts....
If the better pressure was higher, then raise the back pressures 20% (so now 10% higher than the "good" front pressures) and try again.
If the better pressure was lower, then lower the rears 20% and try again.

Repeat this process until you reach a point where there is not much difference when the pressures are swapped.

If you can't make much sense of it at 10% difference you could try more, but be aware the car could get very unstable and lose it...
Paul Walbran

Sticky 185s, run at 19 psi cold. wear to the edges of the tread. Sticks like the proverbial; I can corner on 2 wheels. I run the stiff sidewalled ones about 20 cold; both sets warm up a lot and get to 25-30 when hot.

There's 2.5 degrees of -ve camber on mine (not that you can tell...)


Rob Armstrong

>>For lower aspect ratio and lighter cars less pressure is needed.<< Thanks Paulthat the one I got confused about.

I don't know, just wondering, perhaps the difference between Aus and NZ to England/UK might be a difference in road/track surface, the weather and the make up of the same tyre for different countries/region or a permutation/combination of all three.

Wouldn't the setting/testing of the tyre pressures be the last on the suspension set up but then having established the correct pressures would further fine tuning of the rest of the suspension be required and bring you back to fine tuning the tyre pressures again?

Nigel Atkins

Tyre design is a key parameter and some race tyres cetainly dont need as much pressure. That said, Rob your sidewalls are quite distorted and my bet is the inside of the tread would be lifting off the surface. If it was my car and I saw the tyres like that I'd certainly experiment further with pressures as above. However, you probably have already done so and arrived at the optimum.
There are so many parameters to trade off against each other...
Which is why there is no universal simple solution if this pressure is best"
Paul Walbran

BTW, back in the days (1980-ish) when 70% was a radically low profile, the top driver in one standard production race series found that 60psi was what it took on the left front of a clockwise circuit. It was a tightly controlled class, the tyres had to be proper road tyres (no road legal race tyres) , and he was comfortably clear of the opposition.
Paul Walbran

Bingo - Nigel

Your statement--while a little back to front covers tyre pressure importance--

"Wouldn't the setting/testing of the tyre pressures be the last on the suspension set up but then having established the correct pressures would further fine tuning of the rest of the suspension be required and bring you back to fine tuning the tyre pressures again?"

suspension travel measurements combined with tyre temp readings is the only way to set a race car up properly and when it is set up the handling can be altered by small adjustments to front toe

I know I've pushed high tyre pressures here for (my) midget ,but not all cars are equal
On our Chev racer on a sealed track on slicks the ultimate tyre pressures were (secret,don't tell anyone)12rf 10lf 10rr 8lr
William Revit

I run my A048 175/60 13s at 20 psi for sprints or perhaps a bit lower if it's cold or wet. For longer runs on track probably a bit higher at 22-24.

I once forgot to lower them from my winter storage pressure of 30 and the first practice run was a bit interesting!

The sidewalls are so stiff on this type of tyre that a 600kg car on a wide rubber doesn't want too much pressure.

I'm no expert though, I just set them to what feels best for me and my car.
John Payne

Cheers Paul, Willy.

Toe in is interesting too, on my front suspension set up the supplier's instructions state "tracking must now be set to approximately 1/16" (1-2mm) toe in" whereas a mate in the club says it should be zero or close (bearing in mind my Midget is road use only).

With the amount of negative camber I have too much toe in would surely shave the tyre edges.
Nigel Atkins

Nigel
Reasonable amounts of camber change on a road car won't influence tyre wear as much as incorrect toe settings
0-1 mm toe in for a road car with neg camber is the go usually
Naturally if running heaps of neg camber on the road is eventually going to wear the insides of the tyres
Your mate is right with a starting point of 0 for the track
Most cars toe out on turns (Ackermann angle)
But the rule of thumb is -the faster your race car goes the less Ackermann angle you need and can be changed by fitting different or packing steering arms if required
IF a racer is set with toe in it causes a situation where the car will push a little (feel soggy in the steering)going into a turn and then as the steering transitions from toe in to toe out the steering grips up and feels more direct, Setting toe to 0 or a little toe out makes the steering feel more hooked up right from entering the turn and there's no transition to a different feeling
Unfortunately if left like this for the road the insides of the front tyres cop a hammering
William Revit

Willy,
you have reminded me of what I've been told before, probably a few times, but I'll forget again. I do remember Guy saying toe in would be the cause of tear wear.

Originally with the set up I had very little toe in then for some strange reason I checked the fitting instructions and did wonder if they meant 1.2mm instead of 1-2mm as approx 1/16" but decided to try 1.5mm, not a success so will go back to somewhere near 0.5mm - when I remember! :)
Nigel Atkins

RB, I have a big pile of elderly 185/95 13 Yoko Advans Id like to re-home. I think they are Ao32R in super-soft compound. Very few miles so half worn! One new, unused. They have always been stored in dark dry conditions. These might be perfect for one or two track days.
Clive Berry

Hi All, I thought I'd give you an update to let you know what tyres I bought in the end. It may help others ?

I purchased a set of 175/60 R13 Yokohama A539's.

I did the MG's on Track day at Goodwood back in February and they were brilliant. It was a wet at the start and slowly cleared to a damp track with a drying line towards the end of the day. I pushed the car in every session and they never let go or even gave a hint of doing so. They are the same on the road.

I recommend them for spirited road and the occasional track day driving.

R Bradshaw

Thanks for reporting back, always good to hear results.

Great to hear you got a good result and can recommend them.

Unfortunately the sizes available are too wide and low for me but may suit many others.
Nigel Atkins

Late to the party here, but see you have gone for A539s. They are have been brill in my experience. I have done track days, sprints and hillclimbs on them and they have been great.

I have 175/50s on my 5" rims. They look a bit silly and chuck the speedo off, but allow me to get the car lower. I swap to a set of taller tyres on rostyles for sensible (it's all relative!) road driving.

Malc.

(Hmmmm... can only find "arty" shots of me at Curborough)


Malcolm Le Chevalier

This thread was discussed between 07/01/2020 and 04/05/2020

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