Wider front wheels, anyone done before?

[cooberpedy]

I read somewhere here, that it would be beneficial to have wider front rims and tyres.
I'm thinking of putting 10" rims with 285ers on.
At this stage of my build i think it would be relatively easy to address clearance issues of wider fronts.
Has anyone gone this route and can comment please.
cheers

[Life Saab Itch]

If the tyres are made wider on the inside edge, the steering will be lighter whilst gaining valuble contact patch area on the road. The only issue may be steering lock, but it wouldn't be too difficult to fabricate a couple of lock stops to clamp on the steering rack.

[macgtech]

Life Saab Itch said:

If the tyres are made wider on the inside edge, the steering will be lighter whilst gaining valuble contact patch area on the road. The only issue may be steering lock, but it wouldn't be too difficult to fabricate a couple of lock stops to clamp on the steering rack.

This is correct, and will transform the handling of the car. You will need to reduce the steering lock though. In theory the steering should be lighter, but in practice it doesn't actually make any discernible difference as you have more rubber on the road. We have 9 and 10.5 inch fronts and the difference in weight of the steering is negligible.

[cooberpedy]

That's what i actually thought of, adding width only to the inside of the wheel.
Does that simple lock stop do the job or have you modified the front of the side pods?
I have hooked up a test install with 10.5 inch fronts and have found, that the wheel touches the front of the pods and comes very very close to the water pipe when turned to the right.
Perhaps the overall diameter of the tyre here is to large, it is a 27-68 Michelin.

[macgtech]

You will definitely have issues with slicks - they are generally a much bigger diameter than road tyres. We had to modify the side pods, change the wheelbase and the headlamp covers to fit. Jubilee clips on the steering rack work very well as lock stops. Our front slicks are 285/650R18

[Storer]

cooberpedy said:

I read somewhere here, that it would be beneficial to have wider front rims and tyres.
I'm thinking of putting 10" rims with 285ers on.
At this stage of my build i think it would be relatively easy to address clearance issues of wider fronts.
Has anyone gone this route and can comment please.
cheers

I now have the choice between either 245/30x18 or 285/30x18 front wheels and tyres on my Ultima. I have gone down the reduced scrub radius route and have longer front wishbones and the wheel centres are moved further out in the wheel (as with the Factory 720). My spring/damper top chassis mount is also lengthened and height increased and extensions on the steering track rods.I also have a strut brace.

The 285's do rub on the sidepod on the drivers side. You need to reduce the turning angle too.

The wider tyre does increase grip but also increases steering load at low speeds too. The biggest problem I have found is increased tramlining especially with the square sidewall of the Khumo track tyres. I am still fiddling with camber angle and am about to try 0 deg instead of 1.5 deg negative which is the standard setting.

My front clip is not standard but if you have a standard one you will hit the lights with the wider tyres too.


Paul

[macgtech]

Hi Paul,

How did you find the change to the longer front wishbones?

[Storer]

Hi Jonny

The change in wishbone length has involved quite a lot of work and expense. I think it is the only way to fit wider front wheels that do aid front end bite.

I have yet to do a trackday with the stiffer track springs but on standard road springs the wider tyres did make the car more go-kart like on track. Improved braking too. Very impressive and faster than an Atom round Bedford Autdrome, but it is still no race car.

On the road they make tramlining a big issue (as I said above) so I have reverted to 245 for road use. It could be the square edges on the Khumo's as the P Zero's are much more rounded, and I think the camber is another factor.

Paul

[2001ultima]

Ken a fellow member fitted wider front wheels, I believe 1 inch wider on the inside and then mounted 295s. I believe Ken found a way to simply put a turning radious stopper on the steering rack to prevent scrubbing. Im sure Ken will respond once reading this thread.

[2001ultima]

I found the following: http://www.pistonheads.com/gassing/topic.asp?h=0&a... point for front tires while turning

[V8Dom]

Storer said:

I now have the choice between either 245/30x18 or 285/30x18 front wheels and tyres on my Ultima. I have gone down the reduced scrub radius route and have longer front wishbones and the wheel centres are moved further out in the wheel (as with the Factory 720). My spring/damper top chassis mount is also lengthened and height increased and extensions on the steering track rods.I also have a strut brace.

The 285's do rub on the sidepod on the drivers side. You need to reduce the turning angle too.

The wider tyre does increase grip but also increases steering load at low speeds too. The biggest problem I have found is increased tramlining especially with the square sidewall of the Khumo track tyres. I am still fiddling with camber angle and am about to try 0 deg instead of 1.5 deg negative which is the standard setting.

My front clip is not standard but if you have a standard one you will hit the lights with the wider tyres too.


Paul

Paul leave the camber until you have looked at tracking first..

mines now parallel and we are now looking at toe out rather than toe in..

also if you have alot of tram lining double check rear too..

mine was all set up wrong.

Dom

[Storer]

Dom

I have had the suspension (front and rear) set up to the Factory recommended settings and have had the bump steer dialed out too.

I now have all the equipment to do my own checks on front and rear tow (toe?) so I can adjust each time I make a change.

I believe that Ken uses his car mainly on track (I could be wrong!) but I also suspect US roads are much smoother than our UK cart tracks (roads).


Paul

[V8Dom]

Storer said:

Dom

I have had the suspension (front and rear) set up to the Factory recommended settings and have had the bump steer dialed out too.

I now have all the equipment to do my own checks on front and rear tow (toe?) so I can adjust each time I make a change.

I believe that Ken uses his car mainly on track (I could be wrong!) but I also suspect US roads are much smoother than our UK cart tracks (roads).


Paul

ill pm you

[k wright]

2001ultima said:

I found the following: http://www.pistonheads.com/gassing/topic.asp?h=0&a... point for front tires while turning

The wider fronts really made the car corner (after this change I had no choice regarding fitting a dry sump oil system). I have yet to fit the newer light boxes, my cars turn radius is restricted by the original light boxes contacting the outside of the tire. Installing the new light boxes would mean the diagonal return tube on the side pod would be the next thing that would contact the inside tire edge.

I used a PVC pipe that was cut in half, held it around the steering rod under the steering rack bellows to restrict the turn radius. I did this prior to making the front wheels wider after repairing the light box once.

My car is a fairly uncompromising car that does most of it's miles on the road. I have PS2 tires. My camber settings are listed in the thread above. Regarding tramlining noted by others I would bet that an increase in negative camber would have a significant impact on this. I have some toe out at the front but have forgotten how much. Tires will no doubt have a giant impact on tramlining.

Public roads where I live in the USA are without equal.

[macgtech]

The tramlining is mainly down to the high levels of camber and wide tyres. If its a problem try reducing (less negative!) the camber by half a degree