can any on etell me whats the bigest size rims i can go? i was wanting 17 inch all round but would have prefered 245's on rear and 195,s on the front, has any one tryed this?

Although aesthetically pleasing, 17" wheels and tyres do not make for a better ride, inface quite a few people recommend using 15" as they look right for an Indy and the ride is allot better.

The question I must ask is why?

Something like 205 section tyres is man enough for all but the most powerful bike engines.

Going 17" and then putting wide rubber on as well is likely to produce a car that rides like shite and will handle like a pig. You want a car that is driveable on the limit, not one that is skittish and liable to break suddenly away under hard acceleration and/or cornering.

I appreciate big wheels look nice (in some peoples eyes) but the reason you are building a seven (especially a BEC) is for high performance and good handling. All 17" wheels will do is add weight and degrade the ride/handling of the car.

So in summary stick to 13/14 or 15" wheels and enjoy the car more (and spend less too).

Sorry for the rant, I just get frustrated by the general "bigger the wheels the better" mentality. Unless a car is specifically developed and designed with big wheels in mind, they are detrimental to handling and potentially dangerous.

Cheers

Paul

15 inch OZ superleggeras (4.9kg a wheel, very light)

Toyo 888r 195 or 205 tyres...

More than man enough for our application

Right hellfire

i've got 17"s on my indy with 205tyres front and back and it doesn't seem to compromise the ride too much at all, they do look good, but if you go for much wider rear tyres it'll be useless when it's the slightest bit damp, i used to have 285s on the back of my rs2000 and it was an absolute nightmare!!

Ultra low profile tyres need to have a stiffer sidewall to prevent them pinching on the rim when you go over a bump, and the tyres you can get in larger rim sizes are generally designed for much heavier cars than ours, so the ride / handling problem is compounded.
Also, there's weight to consider, you'd struggle to find a 17" wheel / tyre combo that would weigh less than 17-18kgs a corner (and usually more like 20kgs), so considering you could get get a decent 13" combination for 12kgs easily (mine are ~11kgs with relatively heavy Yoko 32s on them) or a 15" set for not much more, not only are you immediately making the car a good 20-30kg heavier, its also the worse possible kind of weight because its unspring, and because its rotating the increased gyroscopic effect means the car is less inclined to want to turn than with lighter wheels.

Chris

Chris is spot on...

The heavier weight slows acceleration and braking as well.. ie its harder to start spinning and harder to stop spinning...

I fancy 13's myself. I went bigger on a previous car and didn't like the ride so I'm going smaller this time. Seems to be a bit of a problem fitting discs though. I'm looking into it at the moment to see the best way around it.

Is it front or rear clearance problems people have with Sierra discs? I have always got the impression that it was rears that caused the problems on MKs etc, which is kinda odd as Im sure Westfield use the Sierra caliper on the back of their cars, and they can run 13" wheels no problem. Maybe they use a different disc, or offset the hub more than MK etc?

Chris

That was what I was wondering. I was thinking about maybe using something like a 240mm disc which should give plenty of clearance. Not sure what size rubber though. Possibly 205/60 on the rear or maybe just settle for 185/60 all round.