tyre knowledge needed

[mro_racing aka Doorbell]

I am coming back to mardave racing and was interested to know back in that days that mardave used to only have two compounds of tyres (soft and hard) does anyone now if the hard tyres are still made or if anyone knows what shore rating they are?

thanks

[JimboJames1972]

The good news, and bad news, is that there are now many compounds available under the Mardave brand.

What surface/track are you racing? For circuit racing, Pink Medium (V54P) are best for the rear. Apply full width additive and you are good to go. I have not raced oval for a few years but the pinks should also be good for there too. Other popular alternatives were the SE compound last time I raced oval.

Fronts are far more open, as far as choice goes, and are a very good way of tuning your setup. The softest popular fronts are the JAP mediums. These will give a LOT of front grip but can be good on high speed, high grip tracks when you run them at extremely small diameters and can drive with only a little steering lock. The rest of the JAP range are graded in shore ratings - 38 is the lowest I think and they go up to 52. Softer fronts give a more progressive corner entry but more total grip; harder shores give a more twitchy initial reaction to steering input but then tend to push on. For me, on circuits, my choice is 46 shore.

As well as compounds, tire diameter and additive application are also extremely important. Larger tire diameters give more sideways grip (due to the side wall flex) but can be prone to grip roll if the side wall rolls under in extreme cornering. Conversely, smaller diameters give less overall grip and can be used to reduce grip roll, especially if the sidewalls are coated in super glue as well.

General thinking is to run the fronts smaller in diameter than the rears. I usually start my rears at about 49mm diameter and my fronts 47mm.

Hope this helps a bit,

James

[mark christopher]

Also contact tyres are more popular now and have a good range, available from any model shop that deals with Schumacher so plenty of places to buy. Which class are you racing? Most popular is 35/37 rear and 47/50 front

[SlowOne]

Er... I think that should read 35/37 rear...!

[mark christopher]

Originally Posted by SlowOne

Er... I think that should read 35/37 rear...!

doh, editied!!

[mro_racing aka Doorbell]

well im circuit racing I tried racing my mardave a year ago but only went a 3 times and I was running Pink Medium on the rear and found some very old mardave tyres when I first raced the car over 15 years ago and it worked very well.
thanks for the advice
just a couple more questions are the Pink Medium that same as contact tyres 35 or 37?
I would like to have the same make of tyre all round if possible but not a big deal if that's a bad idea
I would like a tyre that has little grip at high speed but have grip on the low speed and no grip roll.
is going for a shore rating of 50 is a good idea?

[LongRat]

I'm not sure anyone could be sure if pink meds are the same as anything from Contact. From my experience I'd say they are different. On my circuit Mardave I run the pink meds on the rear and Jap 52 on the front, including sidewall superglue on the front and I tend to run them as small as practical on diameter. Everything JimboJames said in his original response is on the money. I always found the Contact tyres to cause more grip roll and be more prone to chunking than the Jap/pink med tyres.

[JimboJames1972]

Pink Mediums are similar to Contact 35 in shore rating, perhaps a little softer.

However, the blend of rubber is different between the Mardave brands and Contacts. The Pinks seem to have good low speed grip (thanks to the soft shore rating) but offer a little progressive release in grip at higher speeds, probably very close to what you are after I think. It is hard to put into text but Contacts seem to give grip, grip, grip, grip and, if you really push them, they are themn prone to peeling off the rims or grip roll. Pinks give grip, grip and then gentle, progressive slide. Like LongRat says, less chance of chunking this way. At least, that I what I have also found on the various tracks I have raced on.

There is nothing specifically wrong with mixing and matching tire brands, pick what works for you.

Hope this helps,

James

[mark christopher]

I have run contact and Mardave, on my car the contacts were superior, gave a better grip through the race and no grip roll. Only time I have had chunks is if I have clipped anything.make sure there not damaged after use there fine. Nearly all the a finalists at the tamworth nationals ran contacts.as I said earlier far easier to get hold of too, if there peeling off the rim, then quiet frankly your running too soft a shore. Check the tech charts for the nats and you will see we were up to 40 shore rear and still a Max of 50 on the front.

[mro_racing aka Doorbell]

thanks for every1's advice much appreciated
think its made my mind up and im going to use UFRA Pink Med Tyre on the rear as I now they work and most other people seem to use them plus there cheap and will try Jap 50 Shore tyres and Jap 52 Shore tyres on the front

[mro_racing aka Doorbell]

right seems as I didn't have UFRA Pink Med Tyre on the car already but tried the tyres the front is spot on but the rear doesn't work as well with the UFRA Pink Med Tyre so tried the old tyres on there and was perfect so now I'm on the search for what these tyres are (I think from now on I will label up the tyres )
the tyres have a shiny wall on it on one side like the Jap 50 Shore tyres and Jap 52 Shore tyres but is softer was thinkin maybe it could a Jap Medium but not shore as I can only find Jap Medium fronts on mardaves site is this any different or is it just called that because there used on the front ? hellllppppp!!!!!

[JimboJames1972]

As your tires had the smooth, shiny outer sidewall I am assuming that they were a set that you glued yourself rather than a set that was bought trued and glued?

If memory serves, all JAP and UFRA tire donuts have at least one sidewall that is smooth. When gluing their tires up, most drivers have this sidewall on the outside - it is one of the things that makes the JAP/UFRA tires less prone to chunking. Unfortunately, it does not help us identify the tire type...

It is perfectly possible that your "better" tires were JAP Medium fronts that were stuck onto rear wheel rims. I have seen this done several times and, while not common, it is a trick I have seen used by drivers who usually race on small, tight or very high grip tracks when they are looking for more rear rotation in the corners.

UFRA also do a Pink Soft rear compound that offer a little more grip than the Pink Medium flavour. So, if your better tires had more grip than the Pink Mediums then they might have been softs.

So, if you want more grip than the Pink Mediums, try the Pink Softs. If you need less rear grip than Pink Mediums, try JAP Mediums.

Hope this helps,

James

[mro_racing aka Doorbell]

yes I do all my tyres as I have so many rims and I don't run bearings in the front wheels also because I have so many standard rims.
well the rear tyres I ran the smooth side on the inside so they could round off and they are very hard more like a jap 40 shore but a little softer. they don't seem to wear much but have so much grip. btw I don't uses additive on my tyres as cba.
when I used the UFRA Pink Med Tyres in practice it didn't seem to bad about the same as the mystery tyre but by the end of the first race the rear has no side bite at all and after a practice and 2 races the tyre diameter had gone from 50mm dawn to 44mm.
so if I buy the Jap Medium fronts tyres do they still come as 50mm diameter.

[JimboJames1972]

Well, there are some mysteries there...

First off, your tire wear is extremely high. Loosing 6mm in just three races is something I have never heard of before! I know some of the lads at a local club here can loose 2mm off their Contact rears in one meeting (4 or 5 runs, depending on practice) but they run just the one set, apply CS additive each run and their carpet is particularly abrasive. My Pink Mediums last me about 12 meetings with 6 runs per meeting (I do use three pairs though and alternate them after each run, but it still works out at 15-18 runs per pair). I start mine off at about 49 mm diameter and bin them when they get to 46mm.

If you were at 44mm, that would explain your lack of side bite - slim tire walls don't flex as much as high ones do and can therefore offer less grip. Don't run them less than 46mm and you should be ok.

As for the shore rating, I believe JAP Mediums are around 38? If so, seems pretty close to your "like 40 but a bt softer" description.

You certainly used to be able to buy 50mm diameter JAP Medium donuts, and even 50mm JAP medium trued and glued fronts as well as rears. If the donuts are specifically listed as "fronts" I think they will be smaller. Best way to find out for sure is to call Mardave direct.

The high tire wear still worries me though. What surface are you running on and what additives are other drivers using? Either way, running a second (or even a third) pair will eventually pay for itself with less wear.

James

[mro_racing aka Doorbell]

running on very high grip carpet.
I now I don't now if it is down to wheel spin as im the only 1 running a 12x2 brushed motor on 1s lipo as it had a lot of grunt compered to the brushless motors.(I will be changing to a 13.5 brushless soon).
but yer I think I will contact mardave

[JimboJames1972]

Ok, I think it is the motor. That will be a LOT more powerful than a 13.5t, probably more than a 10.5t too?

You will notice a big saving in tires once you switch to 13.5t brushless.

J

[JimboJames1972]

And just to throw a few numbers in there...

A quick search for 12x2 brushed motor specifications comes up with results of around 40,000 to 42,000rpm (at 7.2v) and powers of about 185W

With 13.5t we usually suggest a Kv rating of around 3000Kv which would give you somewhere around 12,500rpm on 1s and 25,000rpm on 2s. Output power is also around the 90W mark (at least as far as 1s goes).

Obviously, one cannot compare directly between brushed and brushless motors - torque characteristics will be different and a lot will depend on timing etc. However, back-of-the-envelope calculations give your 12x2 motor to be roughly twice as powerful as a "standard" 13.5t.

Yep, wheel spin will probably account for your tire wear... ;-)

James

[mro_racing aka Doorbell]

oh I see that would explain it
I see mardave do VJ38 - Jap 38 Shore tyres but are these the same as V54J - Jap Medium Fronts ?

[JimboJames1972]

No, I do t think so.

James

[CrashBangWallop]

For my 4p worth if you are running a Ministock a good balance is JAP50 on the front with 2 coats of superglue on the outside edges and V54PU on the rear this will allow the car to 'rotate' better i.e. rear steer !
This works with a Brushed setup, I have since changed to brushless setup and have gone to Pink Medium on the rear.
But with the Ministock half the battle is mounting the body correctly.

Oh BTW I don't run any additive at all - plenty enough goes down on the track for the grip level to come up in an evening's racing.