Hi guys,

Ive just bought an R1 powered MNR Vortx and I'm impatiently waiting for it to be delivered from the UK over to Hong Kong

The car will only be used on the track, and on racedays it will be pretty much open to use any tire width.

I'm going to get a new set of wheels to run slicks.

What's the optimum width slick and corresponding wheels front and rear?

Can you run 13s? That would make life much easier. Crossplies or radials? Budget?

[Edited on 3-5-11 by phelpsa]

Hi

I'm running 7-21-13 on the front (around a 185) and 8.2-22-13 on the back. Fronts would maybe be better slightly wider but then I would need 8" front wheels

I run Crossplies and they cost me 880.80 in A15 hillclimb spec. If you were in the uk I would recommend phoning Bmtr and ask for the motorsport team for some advice.

Cheers

quote:

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Originally posted by paublo999

I run Crossplies and they cost me 880.80 in A15 hillclimb spec.

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quote:

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Originally posted by phelpsa
Can you run 13s? That would make life much easier. Crossplies or radials? Budget?

[Edited on 3-5-11 by phelpsa]

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Hi

Just a word of caution - if it's not dry sumped then I would recommend running it with standard road tyres to see what happens oil pressure wise (in long corners) before investing in slicks.. you might have some engineering to do.

When you're happy then move on from there, sizes are roughly as per paublo says (unless you've got mountains of power) as for brands and compounds chat to your local suppliers as you'll be operating in temperatures we don't see too often over here!

MNR told me specifically to not run Bias ply. When we design our student fsae car every year we START with the tire data and build the car from that so I'd have to assume the MNR would not work well for bias...

that said I see hillclimb mnrs on youtube that run formula ford size bias play abc10's....

It's a little tough for me to figure out what to do as well... all the nice compound radials aren't available in the correct diameter in 13's in the US... only the bias plys are.

Seems mnr specs formula ford size tires so I would try to follow those guidelines... keeping the correct diameter is super important (we aren't talking gearing here... we are talking geometry) so I'm pretty hesitant to go changing around on their design but I'm going to have to pick the lesser evil of the two (wrong construction or wrong diameter).

PS they recommend a "A048-185/60/13 and 205/60/13"... All in all if you have an r1 engine I would keep pretty close to these specs... f/r tire temps should be somewhat even with your weight distribution (not speaking from experience here... just guesses). 13x7 front rims 13x8 rears... the wheel width is less important with radials but with bias play its going to make a huge difference. I've seen 205 front and 225 rear but in a car this light that is the max you want to go... you have to start worrying about if the tires will even get up to temp and the added unsprung weight/rotational inertia

A048-185/60/13 and 205/60/13 comes out to 22.7 dia rear and 21.7 front... try to keep to those diameters.

[Edited on 3/5/11 by ffrgtm]

Hi Crafty,

We run 3 Vortx r1 track cars in Australia.

In our experience the following should help you:-

Wheels Compomotive CXR 1381 13" x 8" offset ET18 front & rear

Tyres

Dunlop radial slick 215/525R13 (this is used in a 7 based race series here)

or

Avon radial slick 195/535R13 ( the Avon has the same compound width as the Dunlop)

For wets we have the slicks hand cut.

We've found the Avon is the quicker tyre of the two, and much sharper in its response. Which our experienced openwheeler drivers prefer. The Dunlop is not quite as fast, but more predictable, and a lot cheaper to buy down here.

Hope that helps. Feel free to email me if you need more info.

Regards

Greg - Redback Motorsport

Thanks Greg - you have mail.

I have driven a Caterham Fireblade with 8's all round and felt it could do with more rubber on the rear. However, it had a live axle. I havent driven my car so I dont know if it will have the same issue.

In an ideal world, I would drive my car and get a feel for it before buying the wheels, but this is not that simple in my situation. The car is being delivered to Hong Kong, then I have to pay an import bond to get the car into China. Any spares that go with it are included in the bond, but it is difficult to get spares in later.

The Caterham guy gets his tyres from a Forumula Renault team who are stationed at the track. They have a way of getting tyres in.

They are running:

Michelin FR2.0 (dry) and P220 (rain) 16 x 53 x 13 on 8" rims (front) and 23 x 57 x 13 on 10" rims (rear)

So the easiest solution for me is to run their tyres. They would however prefer to sell sets, rather than just fronts, but they will sell just the fronts if I give them enough warning.

The car arrives in 10 days so I need to buy a set of wheels to send over with the car.

I am not limited by race regulations to tyre choice, so I can run any width I like.


Has anyone run 10" wheels on the rear of a BEC MNR?
If so, what offset?
Was it too much rubber?

[Edited on 5/5/11 by crafty]

Does anyone know if 10” rubber fit on the rear using an 8” rim with ET18?

If yes, then the simple solution is to order 4x8" rims and experiment with rubber.

Hi, crafty!

I have seen in your pics in another thread that you have a 5VY engine, but on the pic it seemed as though the engine had the R1's standard breather setup.



I know from experience that this is not suitable for track driving. If it is indeed so, and you didn't have the breather modifications made to the car, don't take it on a track, or you'll kill your engine in a few laps. Or ask Greg (road warrior), he has helped me as well with the mods.

Take a look at the link below, have a good read through.

Linky to breather mods

In case the breather mods are done though, apologies...

Gergely

I think you will struggle with 9" never mind 10" and I think it will be massively over tyred.

7's run narrow tyres for handling. I get away with wider tyres for sprinting as the start is so crucial. I would maintain that a 185/195 front and 205 or 215 would be about right.

Thanks for the tips guys.

The crankcase breather mod is being done before any track work. Its pretty hot over here so I'll be watching oil temps to see if I need an oil cooler.

Ive ordered a spare set of 8" rims for slicks and also a Flatshifter Expert + Max + paddles.


Only a few days to go and the car will be in Hong Kong. I'm planning of getting some video of the MNR and my Ultima tearing up the streets of Hong Kong before sending the MNR to China.