NEW TYRES FOR CHIMAERA 4.0HC

[captaintact]

Hi Guys
Will soon need 2 new front tyres. Currently shod with TOYO T1-Rs 215-40-17-Z (heavy without PAS!). The rears are TOYO T1-R 245-40-17-Z but they seem ok for now.
I'm in SE London. Anyone know a good (and cheap) supplier/fitter. Is it best to fit more of the same or are there other suggestions? I only drive "normally" on the roads/motorway. NO track stuff or indeed over enthusiastic driving. Boring i know but i bought the car for it's looks etc
Cheers
Graeme

[SILICONE KID]

These are a very good tyres.
http://www.camskill.co.uk/products.php?plid=m54b0s...
I prefer them
over Toyos ,and to save money i buy from Camskill get them delivered and pay a local fitter 6 pound per wheel including balancing .Toyos are a budget tyre but due to demand they are ridiculously expensive.

Edited by SILICONE KID on Wednesday 24th November 17:31

[Milky400]

Camskill all the way, just ordered some falkens for the volvo, cheap as chips

[darkcat]

SILICONE KID said:

These are a very good tyres.
http://www.camskill.co.uk/products.php?plid=m54b0s...
I prefer them
over Toyos ,and to save money i buy from Camskill get them delivered and pay a local fitter 6 pound per wheel including balancing .Toyos are a budget tyre but due to demand they are ridiculously expensive.

Edited by SILICONE KID on Wednesday 24th November 17:31

yeah when i bought my t1r's last feb they where like 70 each, but they have shot right up.

[Chris71]

How much would you expect to pay to have the tyres fitted independently if you bought them from someone like Camskill?

Also, Graeme, have you thought about going down to the OE-spec 205s if the steering is heavy? I say that because that's what I'm planning to do on my non-PAS car too.

[finestjammy]

Chris71 said:

Also, Graeme, have you thought about going down to the OE-spec 205s if the steering is heavy? I say that because that's what I'm planning to do on my non-PAS car too.

I think I'll do this too once they are worn. I've got 225's on imolas with NO PAS

[Chris71]

finestjammy said:

Chris71 said:

Also, Graeme, have you thought about going down to the OE-spec 205s if the steering is heavy? I say that because that's what I'm planning to do on my non-PAS car too.

I think I'll do this too once they are worn. I've got 225's on imolas with NO PAS

225s here too. On 18" wheels.

I'm going to look like Mr T's slightly paler cousing after a few more drives with that steering.

[captaintact]

Hi Guys
Yes i had thought of reducing size as i'm not a racer. Does this mean i have to change the profile from 40 as well? My rears are 245-40-17 Z
How would the car handle as there is plenty of life in the rear tyres
The wheels are 17" front and rear
Cheers
G

[Chris71]

Well, the tyres are 55 profile on the front normally, so the car is non standard anyway. I guess this brings the rolling radius closer to what it would be on the 15" wheel.

As you probably know that 55 (or 40) figure is the height as a percentage of the width. i.e. The height of your tyres is 40% of their width. Because that's linked to the width it means that narrower tyres will have shorter sidewalls too, so a 205 width tyre, for example, will have a smaller rolling radius than a 225 of the same profile. So going for a narrower tyre will actually put you closer to the rolling radius of the original 15" wheel.

The other thing to consider is stiffness. The height of the sidewall is effectively like a lever. The taller the tyres, the more they will deform over bumps and when the car goes round corners, making them effectively softer.

So those are the 'rules'. I leave it to someone with more experience of Chimaeras to suggest what you specifically want to do. Personally I'm going down to 205s on the front and will probably run 4-litre spec rear tyres (225s I believe) to compensate. I am a racer, or at least a track dayer, but I'd rather trade the last bit of dry grip for a bit more progression and feedback. I think the manual rack is a bit overwhelmed with the wider tyres on.

[Milky400]

[quote=Chris71]

How much would you expect to pay to have the tyres fitted independently if you bought them from someone like Camskill?

quote]

local guys charge a tenner in vat per side

[captaintact]

Thanks chris71

As this is my first Chimaera that came with 17" Wheels back and front shod with TOYO T1-Rs. 215-40-17 and 245-40-17, i do not know how a "standard" car would ride. Certainly my car rides very hard and the steering is not only very heavy at low speed but quite vague over bumps and potholes were it is easily thrown off. To be honest my Alfa 164 handles MUCH better! As for the TVR being on rails.....mmmmmmmmmm i'll get back to you on that.....maybe on a track?

I wish to keep the 17" wheels which are great so to keep the overall size of the wheel/tyre if the standards are 205-55-15 what profile is needed for a 205 on 17" wheels? Sorry for being a bit slow on this!

As the rears do not need to be changed yet, how would the handling be affected with what would be a hard ride on the rear and a "softer" ride on the front?

Out with calculators then............

[dog man]

Mine is on Imola alloys with Falkens, not having any other I cant comment but it grips very well and they seem progressive enough. They have had a reasonable wear rate on other cars which I've had Falkens fitted to.

[Chris71]

captaintact said:

I wish to keep the 17" wheels which are great so to keep the overall size of the wheel/tyre if the standards are 205-55-15 what profile is needed for a 205 on 17" wheels? Sorry for being a bit slow on this!

As the rears do not need to be changed yet, how would the handling be affected with what would be a hard ride on the rear and a "softer" ride on the front?

Out with calculators then............

This tool is quite useful for that sort of thing:
http://www.club80-90syncro.co.uk/Syncro_website/Te...

With regards the tyre stiffness, there will be a change, but I don't know how noticeable it'll be. It'll tend to alter the understeer/oversteer characteristics if the rate of change of slip angle is altered on one end relative to the other; it may well affect the steering feel (theoretically even if you change the tyres on the back); and it'll obviously affect the ride.

I would hazard a guess that softer tyres on the front will lead to better feel in terms of slip angle feedback, a slightly softer ride and perhaps a more progressive loss of grip, countered by less steering precision. The slip characteristics at one end have a knock-on effect at the other (hence why you can feel what the rear tyres are doing through the steering on the fronts) so it's difficult to tell how the understeer/oversteer characteristics would change. Conventional logic dictates that softening one end overall should slow down the rate of change of the slip angle at that end, which would imply more oversteer (or less understeer).

...As you can probably tell, though, my knowledge of this subject is largely academic and you're far better off talking to someone with the same wheel/tyre combo that you're planning to use. I don't think you'd go far wrong for road use with any of the common retro-fit options.

[spend]

Chris71 said:

I would hazard a guess that softer tyres on the front will lead to better feel in terms of slip angle feedback, a slightly softer ride and perhaps a more progressive loss of grip, countered by less steering precision.

You are not on rails, more contortion of the wall/tread can actually improve steering ~ it's a fluid thing IMHO.

[captaintact]

Thanks chris71 for the link re tyre options etc. Very interesting with many options available. After looking in "The bible" it seems there were a few standard options for the 4.0 Chim depending on year and PAS. I assume that the gearing and speedo were recalibrated from 1996 when the wheel/tyre sizes changed?
It seems the previous owner has changed the wheel/tyres on mine to 17" but going by the on line calculator on the link, it seems they used the post 1996 tyres with PAS as their reference and not the pre 96 without PAS which is mine! Putting the various options in it means that my front sizes are not correct and hence the very hard ride! I wonder was the suspension changed post 96 too to make up for the naturally harsher ride of lower profile tyres? for anyone interested the original standard set-up for my car according to the bible was:

FRONT - 205/60ZR15
REAR - 225/55ZR16

The current spec is:

FRONT - 215/40ZR17
REAR - 245/40ZR17

ALL Toyo T1-R

The current size on the front would definitely be the reason for the VERY harsh front ride and vague steering on "normal" potholed roads whereby the slightest thing throws the car off line!