the logic of fatter tyres / wider track
Discussion
So I am updating the wheels and tyres on my Chim and was wondering about fitting wider wheels / tyres than standard. From what I have read, you can get 18 x 9 with 255 on the back and 17 x 8 with 225 on the front.
I am updating the suspension at the same time.
What will the impact of fitting the above be? Will the car corner better or worse than if I had 17 x 7.5 and 18 x 8 as per normal SP12 type upgrade?
Many thanks,
Shabs
I am updating the suspension at the same time.
What will the impact of fitting the above be? Will the car corner better or worse than if I had 17 x 7.5 and 18 x 8 as per normal SP12 type upgrade?
Many thanks,
Shabs
Hi Shabs! Cant see any probs. 17/18 rims work really well with good adjustable shocks. I have Toyo R888's on my car which are the road tyre equivalent to 230 front and 255 rear. The rears foul the arches on heavy cornering/bad road undulations, so i have fitted even stiffer springs to control body roll. Also jacked up the ride height a little.
What are you after ride quality wise / handling wise?
Jon
What are you after ride quality wise / handling wise?
Jon
Hi Jon,
I like your suspension setup, your Chim goes like stink through the twisties. My Chim gets used for only three things: driving like a mad man trying to keep up with you on hoons, driving like a mad man on my own to build confidence for hoons and driving on the motorway to get out of London to do the above. That said, what I am after handling wise to suit my needs is:
1). High speed motorway cruising at 100+ leptons without the front feeling light and spongy. To fix this I am hoping that bigger wheels with lower profile tyres and a front splitter will do the trick
2). Undulated road handling. Currently with standard wheels and tyres and two leaking rear shocks along with shot to hell bushes and a geo that has never been done, I have a pretty horrible time on anything above 40 leptons on a lumpy b road. I want it to soak up road undulations and inspire confidence in a straight line on b roads
3). I want it to corner with less body roll and a lot more directly. At speeds of up to 30 leptons I can literally lotus it through twisties and it holds on beautifully. I want to be able to do that at higher leptons
4). For completeness, potholes and broken road surfaces, I don't care if it is hard and crashy, the less so the better but I care a million times more about the top 3.
I have been thinking hard and instead of getting breaks, wheels, tyres and shocks done at once, I am going to fit better quality shocks like Nitrons over Gaz. I was going to go Compomotive MO6 18x9 and 17x8 but now I am thinging that team dynamics would be fine so long as they as they come in the right size and offset. Tyres, I would love something a little more hardcore than TR1's but a little less hardcore than R888's, not sure if such a thing exists but I am after a harder, flatter ride and a progressive let go in the back while I learn to drive it.
I know you spent ages getting your handling set up the way you want it. Any suggestions and pointers would be much appreciated.
Many thanks
Shabs
I like your suspension setup, your Chim goes like stink through the twisties. My Chim gets used for only three things: driving like a mad man trying to keep up with you on hoons, driving like a mad man on my own to build confidence for hoons and driving on the motorway to get out of London to do the above. That said, what I am after handling wise to suit my needs is:
1). High speed motorway cruising at 100+ leptons without the front feeling light and spongy. To fix this I am hoping that bigger wheels with lower profile tyres and a front splitter will do the trick
2). Undulated road handling. Currently with standard wheels and tyres and two leaking rear shocks along with shot to hell bushes and a geo that has never been done, I have a pretty horrible time on anything above 40 leptons on a lumpy b road. I want it to soak up road undulations and inspire confidence in a straight line on b roads
3). I want it to corner with less body roll and a lot more directly. At speeds of up to 30 leptons I can literally lotus it through twisties and it holds on beautifully. I want to be able to do that at higher leptons
4). For completeness, potholes and broken road surfaces, I don't care if it is hard and crashy, the less so the better but I care a million times more about the top 3.
I have been thinking hard and instead of getting breaks, wheels, tyres and shocks done at once, I am going to fit better quality shocks like Nitrons over Gaz. I was going to go Compomotive MO6 18x9 and 17x8 but now I am thinging that team dynamics would be fine so long as they as they come in the right size and offset. Tyres, I would love something a little more hardcore than TR1's but a little less hardcore than R888's, not sure if such a thing exists but I am after a harder, flatter ride and a progressive let go in the back while I learn to drive it.
I know you spent ages getting your handling set up the way you want it. Any suggestions and pointers would be much appreciated.
Many thanks
Shabs
Morning shabs,
Good choice with Nitrons. As standard they come with 325F/275R springs. I have upgraded these to 400F/325R for a year and as from yesterday to 475F/400R. The former is a great spring rate for the bumpier twisties whilst maintaining some ride quality. The 475F/400R is a bit more hardcore but bloody hell is it good! Dont be tempted to harden the shocks to stiffen the car as this will make it crash and skip over bumps. I currently use 10 clicks from hard on the front and 12 from hard on the rear for the 475F/400R springs.
Fitting Steve Heaths drop links front and rear has also improved the roll of the car by making the anti roll bars work as they should and most importantly they work smoothly. I.e dont kick in.
The low profile tyres do make a big difference when the rest of the suspension is being addressed. I really did not like the sidewall movement in the higher profile standard tyres.
Know what you mean about the gap between the T1R's and R888's. To be honest the only negative i have with the tyres is cost and aquaplaning. Are you going to be using your car in the heavy rain? If you are then dont fit them. If you get caught out in the rain and there is standing water about the just drive accordingly and keep the speed down. Having said that the grip level i get from the 888's in the wet is higher than with the T1R's!! I dont get much droning or tramlining. This may be more a feature of the level of geo you have. A more aggressive geo could cause more tramlining which aint great for motorway driving.
Have to say i am very happy with the way my car handles now. Going round Brands on Monday, so i'm sure i will find that the brakes are not good enough blah blah blah...
Will take you for a passenger ride in the car next time we meet.
Jon.
Good choice with Nitrons. As standard they come with 325F/275R springs. I have upgraded these to 400F/325R for a year and as from yesterday to 475F/400R. The former is a great spring rate for the bumpier twisties whilst maintaining some ride quality. The 475F/400R is a bit more hardcore but bloody hell is it good! Dont be tempted to harden the shocks to stiffen the car as this will make it crash and skip over bumps. I currently use 10 clicks from hard on the front and 12 from hard on the rear for the 475F/400R springs.
Fitting Steve Heaths drop links front and rear has also improved the roll of the car by making the anti roll bars work as they should and most importantly they work smoothly. I.e dont kick in.
The low profile tyres do make a big difference when the rest of the suspension is being addressed. I really did not like the sidewall movement in the higher profile standard tyres.
Know what you mean about the gap between the T1R's and R888's. To be honest the only negative i have with the tyres is cost and aquaplaning. Are you going to be using your car in the heavy rain? If you are then dont fit them. If you get caught out in the rain and there is standing water about the just drive accordingly and keep the speed down. Having said that the grip level i get from the 888's in the wet is higher than with the T1R's!! I dont get much droning or tramlining. This may be more a feature of the level of geo you have. A more aggressive geo could cause more tramlining which aint great for motorway driving.
Have to say i am very happy with the way my car handles now. Going round Brands on Monday, so i'm sure i will find that the brakes are not good enough blah blah blah...
Will take you for a passenger ride in the car next time we meet.
Jon.
Just a further note about the tyres!
I have not yet found a tyre which grips grips grips and then bang breaks away sending you into a bush. I thought that the 888's would behave like this but this is not the case. I can still easily maintain a noticeable and controllable drift of the rear end around corners with these tyres. I think the two major factors with this are driver skill (keeping the foot in and not lifting when the traction reduces) and geo setup. The toe-in on the rear can have a marked effect on the liveliness of the rear. I dont know much about the details of this but Derek (abs shocks) can advise you on this next time he is at a Herts and Beds meet.
Jon.
I have not yet found a tyre which grips grips grips and then bang breaks away sending you into a bush. I thought that the 888's would behave like this but this is not the case. I can still easily maintain a noticeable and controllable drift of the rear end around corners with these tyres. I think the two major factors with this are driver skill (keeping the foot in and not lifting when the traction reduces) and geo setup. The toe-in on the rear can have a marked effect on the liveliness of the rear. I dont know much about the details of this but Derek (abs shocks) can advise you on this next time he is at a Herts and Beds meet.
Jon.
Hi Chimjunkie,
thanks for the detailed posts, the R888's do sound good if they progressively let go and don't just snap. Very good point about using the spring rate and not the damper rate to control cornering stiffness. I think I am going to start calling around and will chat with the guys at abs shocks to see what I can organise. Did they also do your geo orcdid you get that set up somewhere else?
What exactly do the Steve Heath drop links do? Is it something to do with relocating the arb's?
Do you have a front splitter on yours?
Cheers,
Shabs
thanks for the detailed posts, the R888's do sound good if they progressively let go and don't just snap. Very good point about using the spring rate and not the damper rate to control cornering stiffness. I think I am going to start calling around and will chat with the guys at abs shocks to see what I can organise. Did they also do your geo orcdid you get that set up somewhere else?
What exactly do the Steve Heath drop links do? Is it something to do with relocating the arb's?
Do you have a front splitter on yours?
Cheers,
Shabs
Shabs said:
What will the impact of fitting the above be?
It will dramatically change the ride quality, handling and grip. Whether it's for better or worse will depend how well it's set up (and you as a driver want from it). However well it is set up you are likely to be sacrificing ride quality.I agree with GreenV8s
Reading this there is a loss of perspective relating to wheel, tyre and suspension options. When a car is developed the individual wheel corner system is part of the overall suspension system, the body and chassis acting as a beam between the front and rear influencing overall suspension and handling qualities. Torsional and beam chassis strength becomes important and is very influential.
TVR’s do not need a hard racy setup for best road handing qualities. Neil Anderson achieved an excellent setup for the road car with the chosen tyres, wheels and suspension bearing in mind the type of customer they attracted to the fold form alternative manufacturers.
Let’s take the wheel and tyre, do you see Formula 1 cars running around with 18 inch wheels and low profile tyres? They don’t use them and retain higher aspect ratios because the tyre wall forms part of the suspension, flexing in conjuction with ultra stiff suspension system’s they use. If you go low profile you may need a softer spring to compensate the lack of movement in the tyre wall. Too often larger diameter wheels are fitted with low profile tyres with resultant poorer handling and a tram lining affect because the lower profile or wheel offset not been maintained or adjusted accordingly.
An interesting dimension is the distance measured on the road surface between the Kingpin angle and Wheel centre line intersection points, race cars will go for minimum distance making the steering light, direct, accurate but twitchy. This would be tiresome on the road and impossible to drive with one hand as many drivers do. Too large an offset and the steering becomes labored and insensitive.
Buy wheel and tyre setups that have proven application. Too many buy these wheels for looks alone, promoting their abilities to justify the grand or so they have spent. Choose wisely.
Track use can benefit from reduced wheel offset to generate direct feel steering and improved cornering accuracy, as track surfaces are very smooth. You can also get away with lower profile tyres and stiffer springs bearing in mind that shock absorber valving must match the spring rate.
If you want a good road track set up 500lbs front and 400lbs rear spring rates work very well on 16” rims without being too harsh or changing the balance of the car. This is an excellent road/track setup, but it is also important to have the tow in set up correctly as well for the correct usage.
Sorry to harp on, but don’t buy wheels for looks alone, you may be disappointed.
Manufacturers seldom get it wrong. -I would stick to 500-400 springs and 16” all round, these having the ability to carry a wider 225 tyre on the front, whilst retaining harmony with the rear. A well proven set up that works.
Reading this there is a loss of perspective relating to wheel, tyre and suspension options. When a car is developed the individual wheel corner system is part of the overall suspension system, the body and chassis acting as a beam between the front and rear influencing overall suspension and handling qualities. Torsional and beam chassis strength becomes important and is very influential.
TVR’s do not need a hard racy setup for best road handing qualities. Neil Anderson achieved an excellent setup for the road car with the chosen tyres, wheels and suspension bearing in mind the type of customer they attracted to the fold form alternative manufacturers.
Let’s take the wheel and tyre, do you see Formula 1 cars running around with 18 inch wheels and low profile tyres? They don’t use them and retain higher aspect ratios because the tyre wall forms part of the suspension, flexing in conjuction with ultra stiff suspension system’s they use. If you go low profile you may need a softer spring to compensate the lack of movement in the tyre wall. Too often larger diameter wheels are fitted with low profile tyres with resultant poorer handling and a tram lining affect because the lower profile or wheel offset not been maintained or adjusted accordingly.
An interesting dimension is the distance measured on the road surface between the Kingpin angle and Wheel centre line intersection points, race cars will go for minimum distance making the steering light, direct, accurate but twitchy. This would be tiresome on the road and impossible to drive with one hand as many drivers do. Too large an offset and the steering becomes labored and insensitive.
Buy wheel and tyre setups that have proven application. Too many buy these wheels for looks alone, promoting their abilities to justify the grand or so they have spent. Choose wisely.
Track use can benefit from reduced wheel offset to generate direct feel steering and improved cornering accuracy, as track surfaces are very smooth. You can also get away with lower profile tyres and stiffer springs bearing in mind that shock absorber valving must match the spring rate.
If you want a good road track set up 500lbs front and 400lbs rear spring rates work very well on 16” rims without being too harsh or changing the balance of the car. This is an excellent road/track setup, but it is also important to have the tow in set up correctly as well for the correct usage.
Sorry to harp on, but don’t buy wheels for looks alone, you may be disappointed.
Manufacturers seldom get it wrong. -I would stick to 500-400 springs and 16” all round, these having the ability to carry a wider 225 tyre on the front, whilst retaining harmony with the rear. A well proven set up that works.
CHGRIFF said:
Let’s take the wheel and tyre, do you see Formula 1 cars running around with 18 inch wheels and low profile tyres? They don’t use them and retain higher aspect ratios because the tyre wall forms part of the suspension, flexing in conjuction with ultra stiff suspension system’s they use.
A good post but spoilt by this. F1 use 13" wheels because of historical reasons, if it were for technological reasons they'd be closer to LMP cars.Indeed great technical post by Chgriff! The 17"/18" rim issue has been thrashed out on many occasion and i recal the general consensus is the best comprimise for style and performance is 17" all round. A fair few people are now moving on to the 17/18 combo for updating reasons and lack of tyre choice for the 15" originals. My experience with 18" rears with 35 profile toyos is that they are a little too low profile and under heavy acceleration whilst cornering the rim can crash if a minor pot hole is encountered at the same time. However, i did find that with Nitrons the ride was perfectly acceptable and the handling much much improved. 40 profile tyres are better, but with 255 width it may cause rubbing on the inner arches depending on the camber setup and how straight the body is on the chassis 
But as GreenV8S says, this kind of change has to be part of a sytem of changes each setup correctly and a proper geo worked out depending on what the user wants from the car.
But as GreenV8S says, this kind of change has to be part of a sytem of changes each setup correctly and a proper geo worked out depending on what the user wants from the car.
Shabs said:
Did they also do your geo orcdid you get that set up somewhere else?
What exactly do the Steve Heath drop links do? Is it something to do with relocating the arb's?
Do you have a front splitter on yours?
Cheers,
Shabs
My geo done at Topcats, but derek and team are very knowledgable and capable.What exactly do the Steve Heath drop links do? Is it something to do with relocating the arb's?
Do you have a front splitter on yours?
Cheers,
Shabs
Do a search on drop links. Steve Heath has posted a detailed explanation on what they are doing several months back.
No front splitter, but would like one which will not rip off every time i go out.
Standard + 20% springs,
Steve Heath drop links,
Pro-Tech's + additional damping adjustment,
10" rear rims, (no bodywork mods),
8" front " , " " "
Polybushed,
1 degree additional front camber.
1/2 " " rear " ,
Ride height set at 160mm rear
" " " " 145mm front, Taken from corner plates on outriggers.
Triple 8's for track use.
The improvement over standard is staggering and still maintain a good ride, (obviously dampers backed off for road use).
Correct ride height is essential as too low a setting doesn't allow the suspension to work correctly.
You may have seen this clip on another thread but I believe it shows what little roll is induced with this setup,(from about 6 mins onwards).
There is no doubt that the car rolled more when ride height set at a lower level previously.
http://www.youtube.com/watch?v=BPqGkItWadQ
Peter.
Steve Heath drop links,
Pro-Tech's + additional damping adjustment,
10" rear rims, (no bodywork mods),
8" front " , " " "
Polybushed,
1 degree additional front camber.
1/2 " " rear " ,
Ride height set at 160mm rear
" " " " 145mm front, Taken from corner plates on outriggers.
Triple 8's for track use.
The improvement over standard is staggering and still maintain a good ride, (obviously dampers backed off for road use).
Correct ride height is essential as too low a setting doesn't allow the suspension to work correctly.
You may have seen this clip on another thread but I believe it shows what little roll is induced with this setup,(from about 6 mins onwards).
There is no doubt that the car rolled more when ride height set at a lower level previously.
http://www.youtube.com/watch?v=BPqGkItWadQ
Peter.
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