OE tyres?

[GeeTee]

Is it possible/allowable to upgrade by using a dedicated race tyre in a class where it is not mandatory? (under 200MPH?)

It looks to me there are minimum OE tyre specs but I cannot find passenger car tyres of the size I require, in the speed rating required by the regs (and the vehicle), so wish to use a dedicated competition-only tyre

[David Leikvold]

I suppose it depends on what size tyre and wheel you want. You could run H rated road tyres and be legal and safe for the speed range you'll probably achieve. If you're looking for a bigger diameter for the rear to help get around the tall VW diff ratios there are other road tyre options available in V rated. What sizes did you want?

Cheers
Dave

[GeeTee]

I can't find the size I want (155 or 165/80 - standard old Beetle size) available beyond T/180km/h. I cannot/will not meet the DLRA's requirement for steel washers etc on otherwise perfect alloy wheels fitted with my existing V-rated tyres (like, why? And how with ball-profile nuts?) so must use stocko steelies. FV tyres are track only, not road-legal so don't carry sidewall speed/load ratings. I am attempting to find out from the manufacturer what their paperwork says about actual speed rating. My mates race on them to 210+ kays.... But... there's no rating on the tyres so that might be a problem at scrute

[Dr Goggles]

The open nut rule is so they can see that the thread is fully engaged, I imagine the steel wheel rule is related to alloy wheels having fractured around the stud section when cars have slid sideways.

[GeeTee]

yeah Doc I have converted my hubs to studs/open nuts (factory VW uses wheel bolts) as it is both 'legal' and more convenient for maintenance (the wheel can be slipped onto the studs so you don't need to hold it up while installing the first bolt) but I really can't work out why alloy wheels require a 'washer' between the nut and the wheel clamping surface. At best, it's a PITA and at worst, it causes non-hub centric wheels (such as what older VWs use) to run out-of-round. That's crude at 60km/h going to the pub, let alone on the Lake...

The more I get into the rules, the more I'm confused. "Tubes are required...". Ummmm, what?!

[David Leikvold]

Don't forget that the SCTA rules have been around for more than 60 years in one form or another and have been constantly evolving since then. A lot of the rules are very old and aren't really relevant any more. The washer / flat plate rule is still in the book because someone might turn up with ratty old alloy wheels that are ready to break anyway. I often get the feeling some cars are built from whatever was lying around the shed when they decided to build a car.
Or they could be wheels from the 70s that need those awful wheel nuts with the parallel shank and really do need a flat washer to stop the hex ripping into the alloy. And if the shank is long enough, without the washer also acting as a spacer the nut bottoms out on the hub before it clamps the wheel tight. Nice! And you have to hold the wheel up until the first two nuts are in place! So the rule's not actually as dumb as it seems, it just isn't relevant for your type of wheel. Modern alloy wheels don't break when a car spins out so the rule is obsolete. I've never seen anyone use a plate, it just isn't good engineering.

The roll bar rules also specifically preclude the use of pipe fittings , so you can just imagine what sorts of junkpile turned up all those years ago expecting to race!

NEVER fit tubes to tubeless tyres. See my PM.

Cheers
Dave

[GeeTee]

...yeah I totally get the fact the rules have heritage around 60 years old. That's kinda cool! But with no published exceptions/updates for modern stuff (in some aspects, anyway), I am completing my vehicle fit-out in a fog.

Yeah I have had all those situations with 70s wheels - and one more that is even worse: If you convert VW hubs to studs and use a shanked, closed-end nut with old peg-style Aungers/Cheviots, and the stud is too short due to wheel offset, and you over-torque the nut, you can break the nut where it's necked-down to the shank (at the base of the hex). If the torque is enough to fracture the nut but not totally decapitate it with the socket, the result is a fracture that you won't see....

I have precision-machined alloy wheels and comp tyres here that bump over ripple strips at 200+ km/h at every track in Oz yet the rules require I fit steelies that I belted the dings out of with a mallet, then squeeze on a heavy road tyre that is (by published specs) kinda too wide for that rim... and fit tubes!

I'd like to build my car as safe and strong as possible, with relevant technology and to proven/acceptable standards. I am happy to say my car will exceed every intent of these rules...but it may not comply with them.

Or am I being too pedantic with all this? Anyhow, thanks for the feedback, I need this discussion


EDIT: PM? Nothing arrived...?

[David Leikvold]

It seems I can't send PM's any more. I just tried again and it disappeared again. Never mind. Maybe you should ask around and find a local DLRA scrutineer who might be able to give you some reliable advice. Obviously your alloy wheels and race tyres are the best solution for your car as they are more than capable of handling the speeds your car is likely to do on the salt. Given the experience of another competitor who was running on old Bridgestone RA500s a couple of years back and safely went 150mph it has already been proved your tyres will be up to the job.

Cheers
Dave