325 track car on 17" wheels?

[Lloydie38]

Hi,

Will a E30 track car handle OK with 17" wheels on?

Currently on my 325i track car I have 15" rims but on my road car a E36 328is I have 17's with Michelin Pilot sports on.
These tyres are fantastic but need replacing soon so I was wondering if I get a set of 17" wheels for the E30 and run the old pilot sports on them should it handle OK?

All advice welcome - sorry if this seems a daft question but I'm getting good at them

Cheers

Ian

[Taffy]

The size of the wheel doesn't have alot to do with it, the profile, size and type of tyre coupled with the springs and shocks has the biggest influence. Also, 17" wheels are heavier so affect it detrimentally that way, personally i'd stick with 15's and spend the money on some decent track tyres

[Zayyan]

As above - 15" BBS are the way to go.

[Lloydie38]

I thought so.... It's just with these four Mich Pilot sports 235 x 40 x 17 that will be coming off my E36 it seems a shame to waste them. I suppose I can put them on Ebay

[Andreas]

If your 17inch tyres are old and worn down, then they will have very little grip and won't give you much enjoyment on a track day.

Even though you might think that you have a "virtual slick" and should have lots of grip, these worn tyres are useless. I think this is so because by the time your tyres are this worn down they have gone through so many heat cycles that the rubber has become hard.

I found this to be true of my racing semi-slicks as well. Even though the tyre is not old time-wise (5000km road use and two track days), when I replace the almost slick ones with new ones, there is a lot more grip.

This phenomenon will be even more pronounced with road tyres that last much longer before being worn down.


Alpina B3 2.7 Racecar under construction.

[Lloydie38]

Cheers Andreas, I think they will be going to a mate for him to use as he has just got new tyres and does'nt want to use his new ones on the track which is an old airfield and tears the tyres up a bit!

Noticed you're in Joburg SA, I'm coming down to Cape Town at Xmas and new year to see family, fantastic part of the world, been there a few times but never to Joburg, one day maybe

Ian
Douglas, Isle of Man, British Isles

[polwutna]

Hi.

I have to say that I disagree with Andreas, at least in part. I use old tyres on track purly because with newish road tyres, the tyre will very likely overheat due to block movement. This will eat the tyre quite easily and ruin a perfectly good set of road tyres quite quickly.

Old tyres have much smaller blocks due to the wear, so they move about much less and do not overheat so much. I have used old tyres on a number of occasions and found the grip to be excellent (though still if you are starting off with a crap tyre, it will still be crap when worn - Michelin PS's are v good tho).

I agree with Andreas that the rubber compound will change with both age and heat cycles. The heat going into the tyre on a road is nothing compared to a track so I would only seriously count heat cycling on a track. The colour of the rubber can change giving you some indication that there's something going on within the compound.

Incidentally, some race series competitors choose to have tyres scrubbed before use - 750MC Hot hatch series for example.

HTH

[Andreas]

polwutna, I appreciate your point of view. For some time now I only use semi slicks on the race track and these tyres have very big blocks that do not move around even when the tyre is new. I agree with you that a new road tyre would suffer due to their high tread blocks.

Something to consider though: If heat cycles from road use do not have an appreciable effect on performance, then why don't race teams that require street tyres use old discarded tyres from road cars which would be much cheaper than buying new tyres and scrubbing them to the level of an old tyre.

However, based on what you have said, I would say that maybe Lloydie38 should have maybe at least tried the tyres at the track.

Lloydie38, if semi slicks are not an option, maybe you should try and take something from both my and polwutna's comments and buy used, half-worn tyres which should be cheap, only have half the heat cycles of a worn tyre and not have the high tread blocks which would overheat quickly.


Alpina B3 2.7 Racecar under construction.

[ste]

Road tyres don't suffer from heat cycle damage like your semi-slicks have done.

For what it's worth some clubman racers do obtain 'used' street tyres and have them buffed to use for racing.

Lots of teams don't bother with used tyres though, not because they are damaged due to heat cycles, but because a championship that uses a control road tyre normally sells the tyres to the competitor very cheaply anyway.

E.g. - The championship I raced in used Yoko A539 control tyres. I could buy these from the main sponsor for around £28 each, they would buff them (shave all the tread off brand new tyres!) down to 2mm for an extra few quid. So it's not worth messing with 2nd hand ones.

The main thing that wrecks old road tyres is poor storage, not heat cycles.

Back to the main question - the 17" tyres you have would be terrible on your e30 on the track. If you want more mechanical grip buy better tyres but stay at 205/50/15 on the e30. I used the Dunlop D01J Formula R. They are about £100 / corner if you buy direct from Dunlop but the difference between them and a normal road tyre is huge. You need about 18psi in them when cold as a start point and take it from there.

Yoko, Colway, Kumho etc., etc. all make similart atlernatives to suit various budgets.

[Andreas]

ste, you have more experience than I do, seeing that you raced in a championship, so I want to ask two questions

(1) I already bought 245 / 17 semi slicks and am getting 4 new mags widened to fit. I need at least 17 inch to clear my 325mm 6-pot brakes, but why is it a bad size particularly on the e30 ?

(2) Can you explain what you mean by "bad storage" ?



Alpina B3 2.7 Racecar under construction.

[ste]

1) Why do you need 325mm 6 pot brakes? You're adding much more rotational mass in the larger disc and the larger wheel (and tyre) required to cover the disc and all that weight needs slowing down... it's catch 22.

Use smaller wheels with a smaller disc in it and you've got less to slow down. A set of 4 pots (Willwood or similar) will fit under a standard 15" wheel and with good fluid will stop a 2.7 all day long on track.

In fact a set of standard single pot brakes if serviced well with proper pads, DS2500 or similar and good fluid like Castrol SRF will stop a well driven 2.7 all day long.

You've also got less unsprung weight then and the car will handle better too.

The 245 semi slicks you've bought will offer massive mechanical grip. Are you racing the car in a championship or using it as a track toy? If you're racing it then the mechanical grip will be a huge bonus and your corner speeds will be much higher with the larger tyre - which is obviously good. How have you optimised the rest of the car to use this increased grip?

If you're not racing, you may find the tyres to be too much. It will be much harder to detect the limit so you'll have to react quicker when you overstep it. You'll also have less fun feeling the car work underneath you.

2) Tyres age badly if stored in sunlight, have oil on them, if left on a rim to deflate, if stacked on top of each other, if left for extended periods on a stationary car etc. Buying 2nd hand tyres you don't now how the tyres have been kept or how they have been used before. Some people park by bumping up kerbs. You may buy one of their old tyres which looks 100% fine, but find at 100 mph as you round Copse that the internal carcass is damaged and the tyre has torn itself off the rim and you're now doing a Schumacher heading for the Fosters hoarding. At that point buying a new tyre for a few quid more will seem like a sensible idea.

[Andreas]

I used to go to track days with my standard 260mm discs (no grooves etc), standard BMW pads and DOT 4 brake fluid from any old garage. This setup worked fine, I don't ride the brakes and do about 20-25 laps wereas other guys pull in after 5 laps.

One day I was racing against a Honda VTEC (from one of the local racing series) on a open track day, we both give 110% through the sweep and I leave my braking for the last possible instant. While I am only just managing not to go into the gravel trap, the VTEC just shoots past me before hitting his brakes. I was stunned, nobody beat me like that before.

I swore that one day I will put decent brakes on the car. I had ordered bigger discs and the Wilwood 4-pot calipers. When I looked at the pads and compared them to the BMW pads, they looked slightly smaller and I was bitterly disappointed. After I saw the Wilwood 6-pot calipers, I had to have them, not only were they bigger but the build quality looked good while the 4-pots looked like cheap mass product in comparison.

I do share your sentiments about the weight though. The big 6-pot caliper might not be heavy, but the disc is quite heavy. In addition, I need 45mm wide hub spacers to clear those calipers - more weight.

In my eagerness to outdo the Honda VTEC I may have shot myself in the foot. I guess time will tell.


I don't race in championships, just attend open tracks days and club events. The car is totally stripped and will get a roll cage. To bring the weight down, many body panels will be replaced with carbon fiber parts and possibly include a CF roof and doors - goal is to weigh under 950kg. A coilover suspension is also on the list.


Alpina B3 2.7 Racecar under construction.

[ste]

Interesting - by your own admission your standard brakes would do 25 laps flat out.

You say you were out-braked by a Honda VTEC but not which one.

Did you reach lock-up or were your brakes unable to lock? Was the out-braking due to your tyres having lower coefficient of friction? Was it due to his car weighing less (if a Civic or CRX I'd guess so)? or was it down to the driver?

[fuzzy]

ive never been on the track with my current project e30 yet so i dont know how the 17's would handle but after asking a similar question to people more in the know ill be shelling out on a set of 15's with a decent track day tyres but undecided on manufacturer yet. at least if i roll it and write it off ill still have the good alloys as a starting point for my next project

[Andreas]

Well, not all 25 laps are flat out, I circulate and wait for a guy to race then race him for a few laps and then circulate (1 or 2 max laps) again.

The Honda VTEC was a Civic, do not know if it was lighter.

The brake pedal becomes soft and long in that corner, I cannot lock up the tyres (225 / 15 inch semi slicks all round). My brakes were a definite weak point into that corner - almost crashed an E36 M3 there once due to lack of stopping power.

I am not sure whether he is a better driver or just has a better handling car - I hope it is the latter. Also, I have tried many approaches to that corner and have to admit that I have not figured it out yet, it always feels that it should go better.

Here are two pictures comparing my old brakes with the new ones.
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Alpina B3 2.7 Racecar under construction.

[ollielsd]

I had ordered bigger discs and the Wilwood 4-pot calipers. When I looked at the pads and compared them to the BMW pads, they looked slightly smaller and I was bitterly disappointed.

as braking is based upon torque it is the radius of the pad from the axle and not NECESSARILY the size of the brake pad itself that will benefit the braking effect. hence why bigger disc are better at stopping a car

[Andreas]

ollielsd you are correct, however I was thinking along the lines of heat buildup from repeated hard use as seen on the track.

My disappointment arose from the following reasoning : when the pad is smaller, there is less brake pad material to absorb the quick heat buildup during a hard brake application and thus lead to overheating brakes (pad to caliper piston to brake fluid).

I don't think anyone can dispute this, as everyone will agree that worn down brake pads do not perform well.

The brake pads from the 6-pot Wilwood caliper are however also not exactly what I would call 'massive'. I hope that big aluminium caliper will help to keep eveything cool.

I changed my brake pads on my M3 CSL last week for a track day and I have to say that I was also disappointed with the size of those pads.

So at the end of the day I have to accept that I wont get brake pads that are two or three times as big as my standard pads. The solution to neck snapping brakes must lie elsewhere.

Maybe I should start another topic. Sorry Lloydie38 for going off your topic.


Alpina B3 2.7 Racecar under construction.

[Lloydie38]

No hijack appology required Andreas - it's all good learing stuff and as I'm considering a brake upgrade for my track star your timing is spot on

[ollielsd]

ollielsd you are correct, however I was thinking along the lines of heat buildup from repeated hard use as seen on the track.

aha - i see y u were diappointed

[Taffy]

You can also overtyre a car, 245 sounds far too big and the 6 pots will overbrake the car for sure. The wilwood 4 pots do have a small pad but we compensated by using top drawer pads, Mintex F4R and you'd be amazed how well it stopped with that and some SRF, and some decent lines, total cost £650 all in, bargain.

The best size is (in my opinion) is 205 / 15 on something light like the BBS

[ChrisR]

if you want to use up old tyres then 'grip' tyre softener can be pretty effective in softening them up, illegal for racing though

I'd always stick with 15 inch (bbs) rims as the tyres are as cheap as chips, especially 195 50's

[E30iman]

hey ian jurby is a tyre destroying track and the 525 has always run on what ever second hand 17" tyres i can get my hands on and i find when they are part worn they do seem to grip better than new but on the other hand i would really stick with 15" rims but worth tryin it on 17" then you can let me know for when i get my 325 Goin to miss the big old five series just hope the three series goes as sideways. see you up jurby in a couple of weeks. Glyn

[Lloydie38]

Can't wait to see you're new 325 - we'll have to get a pic of Alex's, your's and mine all together on the track frightening the hell out of everything else with our sideways action

Posh stuff and FWD wrongness on the track - Just give it some boot fella and get the proper wheels pushing you around