Wheel & Tyre combo's - Coupe

[Bearman]

There has been discussion in other forums about wheel and tyre combinations suitable for coupes. For the benefit of coupe owners I thought I'd start this coupe dedicated thread.

Feel free to post up what has worked for you and what hasn't. The pitfalls of incorrect offsets and who has mastered the black art of having nice big rubber on the back without scraping guards.

Post away, it's all good info!!

[Bearman]

As most of you know, I'm running Simmons B45's 16x8 fronts and 16x9 rears. When I was doing trackwork I had a set of Simmons FR17's with track rubber. The fronts were 17x8 (4+1/2" or 115mm backspace) with 235/45x17 tyres, the rears were 17x9 (5+1/8" or 130mm backspace) with 255/40x17 tyres.

Exactly what these relate to in terms of an offset number I do not know. In any case the fronts were perfect on a reasonably lowered car. The rears looked like bicycle wheels!! I can fully understand how people can get really wide large diameter tyres on their coupes with a low profile and hardly any sidewall flex.

See pics below:


The inner sidewall is fairly close to the rear springs and tubs but still enough room to prevent scraping. I had no problems whatsoever at Winton with this setup.




The clearance between the outer sidewall and the inner edge of the guard was huge, I could pretty much get my fist in there. The measurement was (from memory) 60 to 65mm.


Going by this, at this offset it would be possible to run 17x11 with 295 or perhaps 305 rubber and probably not have to lip the guards.

Anyway, hope this info is of help to anyone out there.

Cheers.

[montyv8]

When I upgrade my convo pros I intend on fitting 17x11 Torque thrust IIs.
my rears are currently 15x10, with 0 offset (5" backspace), and 295/50 BFGs. I run an XC disc brake rear.
I have heaps of room on the inside, between the sidewall and the spring etc.

with 2" lowered leaves and 1.5" lowering blocks, If I have three people in the car I get light scrubbing on the outside. My guards haven't been 'lipped'..
If I could get 5.25" backspaced convos I'd be laughing..
I will be getting my spare 9" housing narrowed to XY length shortly, which will eliminate all scrubbing, and allow me to fit decent width slicks ;)
I had an XY length BW diff in there temporarily with my rims and tyres and they sat just right

[Tony xa]

I have a Xa coupe with 18x12s with 3153/30/18 tyres on the rear they are zero offset but this does not mean they will fit other coupes .From my little homework on the coupes it seems the rear guards vary from coupe to coupe and they also may vary from left to right on the same car .
I am a big fan of measuring the car for perfect fitment and custom wheels .

This theard will provide a great place for starting homework for sure and is a very good topic

[Bearman]

Originally Posted by Tony xa

I have a Xa coupe with 18x12s with 3153/30/18 tyres on the rear they are zero offset but this does not mean they will fit other coupes .From my little homework on the coupes it seems the rear guards vary from coupe to coupe and they also may vary from left to right on the same car .
I am a big fan of measuring the car for perfect fitment and custom wheels .

This theard will provide a great place for starting homework for sure and is a very good topic

FANTASTIC!! A great example of new school done right!! Looks great.

It's wierd how the clearance on the left hand side is not as much as the right hand side. I wonder what that's all about? Anyway, so much good info has come out of this thread, keep it comming.

Cheers.

[Auslandau]

Originally Posted by Bearman

FANTASTIC!! It's wierd how the clearance on the left hand side is not as much as the right hand side. I wonder what that's all about? Anyway, so much good info has come out of this thread, keep it comming.

Cheers.

I have been told thats the 'torque side' of the car. I have adjusted the diff, pushing it back to where it should be as it keeps moving to that side. When it hooks up, weight transfers to this side and has the natural slight offset to the left?



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[Bearman]

Originally Posted by auslandau

I have been told thats the 'torque side' of the car. I have adjusted the diff, pushing it back to where it should be as it keeps moving to that side. When it hooks up, weight transfers to this side and has the natural slight offset to the left?

Hmmm.... looks like the thing to do, when measuring up for custom wheels would be to base everything off the left side.

If I were doing a new set of wheels and tyres I'd be going 17" mainly for the availability of a wide range of sizes in tyres. American Racing Torq Thrust II for the old school style.

Keep the info coming!!

[Auslandau]

Mine are the usual 15 x 10 rears (Convos) with 295 352's. They did rub slightly as it does sit low at the back but a quick shave of a few mm on the inside lip solved the problem. 5" is the correct off set for the coupes bum

Agree 100% Tony! Had to take more of the LH side ..... about 4-5mm compared to just 1-2 off the RH!





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[Tony xa]

Yeah I have less room on my left as well by about 5mm

[xbcoupe302]

mine are 15 x 10 275x 60x15 but weld only do a 4.5 inch offset so i had a mate shorten mine to a xy length so no scrubbing now plus i raised it about 2 inches but on the bright side i now have a xy length diff worth $1500 which cost me $200 to shorten

[Bradxbv8]

Hi all, on my coupe im running:
Fronts are 15 x 8 running 235x60 and rear is 15 x 10 running 295x50.
I used the Performance Challengers with 4.5" backspace.
Now my coupe still has the origonal chrome arch trims and has never had the lips rolled, and did not want to do that. I also used a XC 9" LSD and did have to shorten it a whole 17mm per side, but now the clearance's both sides are perfect. If i could have got a XW/XY diff then it should have fitted ok straight up, but was happy with the rear disc set up anyway.
The real killer was having the rear callipers compleatly redone, it cost a fortune.
Brad

[gtxb67]

Originally Posted by Bradxbv8

Fronts are 15 x 8 running 235x60

hey brad, did you find the 235's touched the shell on full lock and/or did you move the wheels forward slightly (caster i think). when my 15 x 8 challengers with 235 x 60 went on they rubbed slightly. after much hassle with the tyre fitter they were finally changed to 225 x 50. i never wanted 235 x 60 - i was told incorrectly i could get 235 x 50 and the height of them would have been perfect. in the end they changed them and they no longer rub and are almost the right height in relation to the rears and how low it is
mine has the 15 x 10 challengers (must be a 4.5 inch backspace i assume) with 265 x 50 yokahama 352's and 15 x 8 with 225 x 50 bridgestone potenza's. the diff is from a 1974 ltd. the rear is lowered around 3/4 inch with an extra 2 inch lowering blocks (2 3/4) and the front has been lowered 2 inches 20 years ago
it has slight rubbing marks on the left rear tyre (probably from the morwell hill climb) and none on the right side. the guards are standard with no rolling. it has not had rear seat passengers since the v8 went in, so maybe if i filled the back seat up i may get some rubbing
it is weird that most people seem to have less room on the left than right on coupes. no one ever seems to rub on the right side

[Bradxbv8]

Originally Posted by gtxb67

hey brad, did you find the 235's touched the shell on full lock and/or did you move the wheels forward slightly (caster i think). when my 15 x 8 challengers with 235 x 60 went on they rubbed slightly. after much hassle with the tyre fitter they were finally changed to 225 x 50. i never wanted 235 x 60 - i was told incorrectly i could get 235 x 50 and the height of them would have been perfect. in the end they changed them and they no longer rub and are almost the right height in relation to the rears and how low it is
mine has the 15 x 10 challengers (must be a 4.5 inch backspace i assume) with 265 x 50 yokahama 352's and 15 x 8 with 225 x 50 bridgestone potenza's. the diff is from a 1974 ltd. the rear is lowered around 3/4 inch with an extra 2 inch lowering blocks (2 3/4) and the front has been lowered 2 inches 20 years ago
it has slight rubbing marks on the left rear tyre (probably from the morwell hill climb) and none on the right side. the guards are standard with no rolling. it has not had rear seat passengers since the v8 went in, so maybe if i filled the back seat up i may get some rubbing
it is weird that most people seem to have less room on the left than right on coupes. no one ever seems to rub on the right side

Gday GTXB67
to be honest i have only gone maybe 200km in the car this hole summer, and yes turining right up the driveway i have to take it slowly or something does touch. At this stage, im unsure just where it is touching, i thought it may have been on the inside. I intend to investigate this further, as time permits. two young kids a house reno and a full on job does not leave much spare time.
The other thing is that i froze and stuffed the LPG mixer and it runs like crap on petrol, heres a laugh, need to loose the 350 single barrel holley and let it breath, all in good time.

[gtxb67]

Originally Posted by Bradxbv8

Gday GTXB67
yes turining right up the driveway i have to take it slowly or something does touch. At this stage, im unsure just where it is touching, i thought it may have been on the inside.

hey brad, i found with that size tyres mine touches on the shell, where i have crudely circled in the pic. where the panel that sits behind the front wheel finishes, the shell leads towards the rear of the car at a 90 degree angle. that is where the tread (not the sidewall) rubbed slightly. it is a height problem not a width. the extra 1 inch from standard creates the problem.
i now have 225 x 50 which makes it easily, but you can move the wheels forward (it is called the caster, i believe) slightly and that will get around it as well. the only problem is that if the wheels are moved too far forward the wheel does not centre in the wheel arch
245 x 50 are ok in height alone, although i believe the width is ok too
hope this helps

[Tha Jack]

Ive got a set of Dragway Flames 15" x 8" 225/60 Yokos on front and 15" x 10" 295/50 T/As rear with 4 1/2" back space. I also have the guards rolled. I still find it rubs on the left side, So Ill be getting the Diff shortened soon.

Does any one know the exact length of an XY 9" Diff Housing? and will 245/50 x 15" tyres fit on 8" rims without scraping on the front end?

[gtxb67]

Originally Posted by Tha Jack

and will 245/50 x 15" tyres fit on 8" rims without scraping on the front end?

i think they will. my old man had 245 x 60 x 14 on his landau. the guards may have been rolled, but his did have 265 with 10 inch rims on the front when he bought it.

the only problem i see is maybe with height but the 50 series will take care of that considering he had 60 series on his
245 x 60 means the tyre is 147mm top and bottom = 294mm of tyre
245 x 50 means the tyre is 122.5mm top and bottom = 245mm of tyre
therefore tyre size is 49mm smaller with 50 series. your rim size will be 1inch bigger than he had but there is almost 2 inches less of tyre than he had. your rim and tyre combo will be 24 mm smaller overall (almost 1 inch smaller <1 inch = 25mm>)

as mentioned above in one of my posts 235 x 60 did not fit, but the tyre in that case was 141mm top and bottom, which means 182 overall. with the 50 series you would be 44mm smaller than those tyres and should therefore not touch where mine did

have a look and see if you have an inch (maybe 30mm) each side of the tyre to clear the suspension and the guard and that could be your best. you could also get a 245 test fitted which would give an idea on the width.

hope this has helped without confusing toooooo much

[RScort]

Sorry to go slightly off topic here, but i have just put some 245's on my XA wagon, and there is a slight rubbing, its only on the letters on the tyres but they are white writing which i want to keep because it makes the car look so much better than not having.

So whats the best way to fix this? I Thought about grinding a tiny little off the inner lip, but not to sure on this. Dont really have the money at the mo to get them rolled so would like to avoid this if possible...

[Auslandau]

If they are rubbing only slightly, and you have an air compressor and speed file, that does the trick if it is only to remove a bit of the inner lip. Just remember to put some primer and paint back on the bit you file off!

Either that or give it a bit and you can have some cheap white walls!!!!



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[gcg2503]

Seeing the pictures of Bearman's XB and Auslandau's Landau are making me want a coupe big time

Those are two awesome vehicles

Well done gentlemen - i love these big hardtops with massive rubber

[fatasslandau]

If your tyres are lightly touching the inner guard it the rear you can massage the inner guard without affecting the outer or your paint. However you will definatly have to lip them.Easier and cheaper than getting diff shortened

[Tony xa]

18s are starting to have a bigger selection than 17s I think .I think this is because super cars seem to use 18x10 and 18x12 up back for traction and the tyres also perform well.

[Bearman]

So these cars are good to drive on with 18"? I know mine felt good with the 17" on the track but doesn't the ride become harsher when you go up in rim diameter? Put it this way, if someone went from old school 15" up to 18" what general differences would you notice?

Maybe 18" are the go instead of 17"??

[Bearman]

Just thought I'd dig this one up. Anyone else with tips, tricks and ideas to share? It's all good info especially for those with projects on the go or those just looking for a change.

Post away!!!

[fullysik.com]

These were 310/650/16's on the rear and funnily enough use to rub on the left hand springs, but only the left.
I thought the watts link may have stopped the sideways movement which it did but obviously not enough with the wide stuff on.



the rears



and the torque thrusts sit good and don't rub with the supercar slicks fitted.

[Bearman]

Yeah, those Torq Thrusts are the go!! What were the specs on them? Rear backspace?

[THE4RD]

I run standard 15 x 10 hotwires on the back and they are OK with 295/50 BFGs.

There is plenty of space to go wider on the inside (near the spring)

On the front:

My 14 x 8 hotwires with 245/50 tyres are OK
My 15 x 7 hotwires with 245/60 tyres = rub against the chassis rail on full lock

I wonder whether a 265/50 on the 15 x 7 rims would rub on full lock?

[gtxb67]

Originally Posted by ianmcw

I wonder whether a 265/50 on the 15 x 7 rims would rub on full lock?

it is my understanding that even though 265's would go on a 7 inch rim, they would not be ideal. they would be forced onto rim that is not wide enough and would not wear properly.
if you look at your 295's on the ten's and look at the sidewall - it is probably comfortable, but probably getting towards the limit. for the 265's on 10's, realistically the tyre needs to compress another 2 inches, which will probably stop the tread pattern from sitting flat on the road.
i would say wear and even handling would not be as good as a 245. the overall look would probably look better with a 245 in my opnion

[cob115]

Originally Posted by gtxb67

it is my understanding that even though 265's would go on a 7 inch rim, they would not be ideal. they would be forced onto rim that is not wide enough and would not wear properly.
if you look at your 295's on the ten's and look at the sidewall - it is probably comfortable, but probably getting towards the limit. for the 265's on 10's, realistically the tyre needs to compress another 2 inches, which will probably stop the tread pattern from sitting flat on the road.
i would say wear and even handling would not be as good as a 245. the overall look would probably look better with a 245 in my opnion

295s have a recomened rim size going on BFGs chart .of 15x8 to 15x10 so i would of thought 15x7 for 265 be ok bit small but ,iv got 295s n 265s on 15x8 n probs cheers pat

[WildPlumXA]

The XA has pretty traditional combo
15x10 Hotwires 295x50x15 T/A's
14x5 Hotwires 245x60x14 T/A's wouldnt mind trying 15x8s either 245x50 or 60s
I have a spare set of 15x10 Hotwires for racing

BTW, the Hotwires were fitted to the XA around 1975 by the second owner soon after he saw the add in a car magazine he bought on his lunch break

XB has a little odd set up
15x15 Weld Pro Wheels 15x15.5x29 M/T Sportsman Pro's it did have 15x22x33's
Final rear tyre will probly be a 18.5x31 or 32
15x7 Weld Pro Wheels 225x60x15's generic radials front

cheers
Lawrence :

[cob115]

Originally Posted by WildPlumXA

The XA has pretty traditional combo
15x10 Hotwires 295x50x15 T/A's
14x5 Hotwires 245x60x14 T/A's wouldnt mind trying 15x8s either 245x50 or 60s
I have a spare set of 15x10 Hotwires for racing

BTW, the Hotwires were fitted to the XA around 1975 by the second owner soon after he saw the add in a car magazine he bought on his lunch break

XB has a little odd set up
15x15 Weld Pro Wheels 15x15.5x29 M/T Sportsman Pro's it did have 15x22x33's
Final rear tyre will probly be a 18.5x31 or 32
15x7 Weld Pro Wheels 225x60x15's generic radials front

cheers
Lawrence :

very nice coupes you have there Lawrence ,want to sell the hot wires?there like rocking horse poop to get here