Tyres - What influences 'grip' the most?

[retro_msport]

They are selling to the public... and if you look at the publics daily drivers they have balloons for tyres, to keep down steering wheel feedback and noise.

we want feedback and dont give a crap about noise.

And yes it may be the red catalogue which is motorsport based, but as any one who goes to a show will know... those catalogues are given out by the truckload and the last thing they want is to have a customer complaing that the tyres are noisy and the steering wheel shakes with every ripple in the road, I'm sure if you phoned up and asked they would advise you of the best tyre for your application..

[graham bahr]

100% with your there retro,

whilst on the subject of a certain red catalog anyone else noticed that they are listing a 9x15 revolution at sensable money

[greenamex2]

Originally Posted by graham bahr

whilst on the subject of a certain red catalog anyone else noticed that they are listing a 9x15 revolution at sensable money

I did, and was straight on the phone to Revolution.

They are only available in Escort Group 4 fitting (4*108 PD and an offset around ET0).

Bugger.

[graham bahr]

thats a shame,

so it means back to expensive split rims,

i could redrill my rear hubs to give me both the escort and beemer pcd and use a blooming thick spacer, but tyres seem now to be a major issue, despite various manufacturers listing them it seems that i cant get a 15 inch slick wider than 200 so the 9 inch rim would be a bit wasted.

[dtype38]

Thanks for that guys, all makes sense. When I see something in black and white, it sometimes makes me doubt my own judgement. (I was taking the maximum size in the "rim range" btw, obviously didn't look at the 48's close enough, sorry)

I'm using is 032R's(inter)/008R's(dry) both 225/60/15 on 15x7 rims at the mo. Would you expect me to get a noticable increase in rolling circumference if I move up to 15x8.5 or 15x9 rims?

[greenamex2]

Originally Posted by dtype38

I'm using is 032R's(inter)/008R's(dry) both 225/60/15 on 15x7 rims at the mo. Would you expect me to get a noticable increase in rolling circumference if I move up to 15x8.5 or 15x9 rims?

What size tyres?

[Al Weyman]

Fred Puhn advocates the wider rim as did my mate who owned a tyre shop and raced a camaro and had privy to a lot of technical data and people.

[graham bahr]

Originally Posted by dtype38

Thanks for that guys,

I'm using is 032R's(inter)/008R's(dry) both 225/60/15 on 15x7 rims at the mo. Would you expect me to get a noticable increase in rolling circumference if I move up to 15x8.5 or 15x9 rims?

Narh, changing the width of the rim will only make a nats cock of a difference, if that much, to the circumference

[dtype38]

Ok, ta. (Denis, the tyre size is half way along the first line of the question ;-) )

[Lukus]

Originally Posted by retro_msport

Nope Dennis, no contadictions from me... totally agree with using the temp gun, as i have a feeling that the tyres running on the outside edge due to the tyre tucking under because its too wide for the rim,

Dennis would you agree to this.. 9" rim with Dtypes tyres fitted, check temps to get pressure and camber setting right for the particular conditions, and then fine tune spring rates with temps and stopwatch

I'm currently reading through this topic, and unless someone has already stated otherwise, don't use a temp gun. Tyre temp is to be checked on a slight angle, and under the surface of the tyre. A few mm into the tread. A temp probe is what should be used.

[dtype38]

Quite agree Lukus. I just bought a Longacre tyre pyrometer with a proper sharp pointy metal probe

[Lukus]

Originally Posted by dtype38

Quite agree Lukus. I just bought a Longacre tyre pyrometer with a proper sharp pointy metal probe

I eventually got through all the posts and found you mentioning the temp probe, instead of the gun, which was good! Had already posted though

Don't necessarily agree with everything that has been said about why wider tyres have more grip, but if you read Racecar Engineering, there was an article about it a little while ago in the very back next to Aerobytes.

I'll have a look around for it. I don't think i can be bothered typing it all out though!

[Goran Malmberg]

Normally the rim should be slighter wider than the tread for the best stability. The mentionend Yokohama R-tire is a street legal tire, and I guess street class racing many times use standard rims. Even oval racing are restricted by rim size therby using wither tread than rims. A tire can be fabricated to work quite well in this configuration, but for ultimate stability the tire should be fabricated for a little wider wheel.
Take a look at racing only tires, Avon or Good Year, especially their wider tires which almost allways recomend a wider wheel.

Dont run wider rims if the tire is made for a narower rim.
Goran Malmberg

[dtype38]

Originally Posted by Goran Malmberg

Dont run wider rims if the tire is made for a narower rim.

Now that's interesting Goran. I was looking at a Yoko A032R off the rim the other day and the inner bead is chamfered and looks like it is designed to run outwards from the rim (ie narrower rim compared to the tyre). Is there any way to be sure what the widest a tyre can run on? I will ask on the Yoko stand at Autosport, but I'm sort of expecting to be told that I should look it up in their brochure, which is quite a narrow rim.

[ubrben]

Originally Posted by Lukus

I'm currently reading through this topic, and unless someone has already stated otherwise, don't use a temp gun. Tyre temp is to be checked on a slight angle, and under the surface of the tyre. A few mm into the tread. A temp probe is what should be used.

You should be taking the temperature at the tread base not half way down. If you use a needle probe, you should be able to feel it scrapping the cords. I appreciate that this might be difficult with road based tyres with harder compounds and thick tread gauges though.

Ben

[Goran Malmberg]

Originally Posted by dtype38

Is there any way to be sure what the widest a tyre can run on?

The tire manufacturer allways have information about tihe ideal rim width.
They also usually tell the smallest and widest width that is acceptable.
Just give the dealer, or better still the Yokohama, a call.
Goran Malmberg

[Tim Falce]

Originally Posted by Goran Malmberg

The tire manufacturer allways have information about tihe ideal rim width.
They also usually tell the smallest and widest width that is acceptable.
Just give the dealer, or better still the Yokohama, a call.
Goran Malmberg

For anyone running Yokos, you could look here for all the information needed for different tyre/rim combinations

[dtype38]

My point entirely Falcey. Goran, If you look up an A032R 225/60R15 on the official Yoko web site Falcemob linked, it says that permitted rim sizes for that tyre are 6.5" or 7" wide. That's for a tyre with an 8.85" wide tread. This is what lead to a lot of the earlier disscussion on this thread. The general concensus so far is that an 8.5" or 9" wide rim would give much better race performance from this tyre, but that the manufacturer wouldn't recommend it because its a road legal tyre and would give a very harsh ride at that rim size. That's why I was curious about you suggesting that tyres might be made that can't cope with a wider than recommended rim.

[retro_msport]

One other thing, on a road tyre the stated tread width is just that, the whole of the tread which on some tyres can go down the sidewall about 10mm, so that 20mm lost, a 205 only has 185 of tread in contact with the ground... its too cold, wet and dark to run out and measure the tread contact on the cars outside.... and compare that with whats written on the side.

[Lukus]

Originally Posted by retro_msport

One other thing, on a road tyre the stated tread width is just that, the whole of the tread which on some tyres can go down the sidewall about 10mm, so that 20mm lost, a 205 only has 185 of tread in contact with the ground... its too cold, wet and dark to run out and measure the tread contact on the cars outside.... and compare that with whats written on the side.

Agreed. The stated "width" is not usually the exact width of the tread, so measuring that and comparing it to the rim width doesn't quite work.

[Goran Malmberg]

Originally Posted by dtype38

My point entirely Falcey. Goran, If you look up an A032R 225/60R15 on the official Yoko web site Falcemob linked, it says that permitted rim sizes for that tyre are 6.5" or 7" wide. That's for a tyre with an 8.85" wide tread. This is what lead to a lot of the earlier disscussion on this thread. The general concensus so far is that an 8.5" or 9" wide rim would give much better race performance from this tyre, but that the manufacturer wouldn't recommend it because its a road legal tyre and would give a very harsh ride at that rim size. That's why I was curious about you suggesting that tyres might be made that can't cope with a wider than recommended rim.

A few example.
Minicup use an 8" rim for a 6,25" tread.
Modified 15" rim for a 13" tread.
ARCA 9,5" rim for a 12" tread.
There are a reason for both this type of rim to wheel relations. But the thing is that each tire is made for a specific rim, and we should not violate this by using anything but the recomended rims.

If we have our own demands for (or rules) we better select a tire that is built for a narrower tread than wheel size. Many racing tires has a pretty wide spann for rims.

I cant explain the reason for Yokohama to use those combinations, but there are more reasons than sidestability that governs rim size. And it might be difficult to get the right answer from Yokohama as the real reason may not be suitable to make public.

Goran Malmberg

[dtype38]

Fair 'nuff. Maybe I'll be better off asking one of their suppliers who go to race meetings. I've met a couple of them and they seem enthusiastic and practical.

[MIdsm]

I have always been told that if too wide a rim is used it may lead to bead popping off the rim in a turn, due to side load, which may cause the vehicle to roll over when the rim digs into the tarmac.

[Tim Falce]

Originally Posted by dtype38

My point entirely Falcey. Goran, If you look up an A032R 225/60R15 on the official Yoko web site Falcemob linked, it says that permitted rim sizes for that tyre are 6.5" or 7" wide. That's for a tyre with an 8.85" wide tread.

I picked up a new Yoko Advan brochure yesterday and it now states 8inch rim size for the above tyre.

[dtype38]

Originally Posted by falcemob

I picked up a new Yoko Advan brochure yesterday and it now states 8inch rim size for the above tyre.

I spoke to the bloke on the Yokohama stand at Autosport and he said "Don't take any notice of the brochure, go for a 9" rim."