HSV GTO Tire Size?

[TRAMS_AM]

I've read conflicting information regarding this subject. Does HSV put 245/35/18 or 245/40/18 tires on their 18"x8" wheels? I do not wish to increase the overall diameter of the tire over the 245/45/17's that are on the GTO stock, which leads me to believe that the 245/40/18 is the correct tire.

Thanks!

[Veritasatis]

Look through this thread (http://www.ls1gto.com/forums/showthread.php?t=173 42). It has links to a few tire size calculators that can answer your question.

[TRAMS_AM]

Look through this thread (http://www.ls1gto.com/forums/showthread.php?t=173 42). It has links to a few tire size calculators that can answer your question.

Thanks! Those tire size calculators are cool!

EDIT: If anyone can tell me for certain what tire is on the HSV GTO I'd be appreciative. I did a search already, honest :).

[Woz]

Thanks! Those tire size calculators are cool!

EDIT: If anyone can tell me for certain what tire is on the HSV GTO I'd be appreciative. I did a search already, honest :).

Sure you did ;-) 19". Pirelli PZero 245/35 ZR19. Pretty much standard on all HSV's now except Coupe 4.

and here is the thread I posted it in
http://www.ls1gto.com/forums/showthread.php?t=5474

[TRAMS_AM]

Sure you did ;-) 19". Pirelli PZero 245/35 ZR19. Pretty much standard on all HSV's now except Coupe 4.

and here is the thread I posted it in
http://www.ls1gto.com/forums/showthread.php?t=5474

I'm sorry, I should have specified that these are for the 18"x8" ones on the VY.

[2IMPULSIV]

My mate had a HSV GTO and from memory the tyres on it were 245/35 ZR18's.

Made by BRIDGESTONE.

Tyre type SO-2's


Hope that helps dude!!




:)

[miscreant]

I thought I have read several places that the 18s carry 235/40R18s.
The 245/35 size in 18 would be 1" toooooo short.

[TRAMS_AM]

I thought I have read several places that the 18s carry 235/40R18s.
The 245/35 size in 18 would be 1" toooooo short.

Another oddity is that Holden puts 235/35/18's on the Monaro, but we put 245/45/17's on ours making our tire a little wider.

So far it seems that the Aussies are all saying 35mm is the correct sidewall hieght.

going from 245/45/17 on a 17" wheel to 245/40/18 on a 18" wheel would yield the same overall hieght, according to the wheel calculators. I think I'll go with that size.

[miscreant]

Another oddity is that Holden puts 235/35/18's on the Monaro, but we put 245/45/17's on ours making our tire a little wider.

So far it seems that the Aussies are all saying 35mm is the correct sidewall hieght.

going from 245/45/17 on a 17" wheel to 245/40/18 on a 18" wheel would yield the same overall hieght, according to the wheel calculators. I think I'll go with that size.
Well, I searched the aussie site and found alot of info where they didn't indicate the wheel size of 18". Alot of people posted 245/35 as the tire, but most of the posts listed 245/35R19, but some did not indicate the "19", so I'm guessing that's still for the 19s. The 19s have been standard on the HSV GTO now, the 18s aren't even available anymore on the GTO from what I can find. However, the Monaro has 235/40 not 235/35:

http://www.holden.com.au/www-holden/action/featurelist?modelid=12001&catid=1002

The new 18" wheel option for the Pontiac GTO come with 235/40R18 tires and last years monaro had 235/45R17 tires.

[TRAMS_AM]

However, the Monaro has 235/40 not 235/35

True, I must have been shrooming. I did some more reading on LS1.com.au about this and found the 245/40/18 discussed (although 235/40/18 came up more often). Apparently there will be no rubbing issues, and the pictures of the tire on the wheel looked fine, so I'm going to go in that direction.

Thanks for researching this also!

[MarkII]

You also have to bear in mind the 245 or 240 figure is the width across the sidewall, not across the tread. 5mm is 1/4", but most tyres which appear to have a smaller cross-section in a larger diameter actually have a wider tread, due to the taper to the tread from the widest part of the carcase, which is greater on a taller tyre. Coupled with the greater rolling radius and dependant on the tyre itself, the 240/35 will likely have a bigger contact patch than the 245/45.

The rolling radius of the two tyres is probably virtually the same - The Monaro's 18" wheels have been an option on SS Comodores (17" stock) for several years until VYII when 18" became standard. The dealers don't do anything but bung 'em on.

[TRAMS_AM]

You also have to bear in mind the 245 or 240 figure is the width across the sidewall, not across the tread. 5mm is 1/4", but most tyres which appear to have a smaller cross-section in a larger diameter actually have a wider tread, due to the taper to the tread from the widest part of the carcase, which is greater on a taller tyre.

This concept first confused me greatly, but after visualizing it on the tire calculator it made complete sense. The only difference between the 245 and 235 is width when they both have a sidewall of 40mm. Since the tolerances with the strut seem to be very close, I hope that my choice of tire doesn't cause rubbing. Top contenders are the Potenza So3, the ECSTA MX, and of course the KD. If anyone has 245/40/18's with any of these tires, please report your findings.

[miscreant]

This concept first confused me greatly, but after visualizing it on the tire calculator it made complete sense. The only difference between the 245 and 235 is width when they both have a sidewall of 40mm. Since the tolerances with the strut seem to be very close, I hope that my choice of tire doesn't cause rubbing. Top contenders are the Potenza So3, the ECSTA MX, and of course the KD. If anyone has 245/40/18's with any of these tires, please report your findings.
No no no. Now he's confusing you!

First, MarkII, there's no "240". We're talking about 245/35R19 tires, 235/40R18 tires, and 245/40R18 tires. There is no 240/XXRXX tire. Now you are correct that the first number is the "section width" or the width between sidewalls, and not necessarily the tread width, and it is true that the lower the aspect ratio, the slightly more tread the tire will tend to put to the ground give the same section width, but it's actually minimal. Typically, the greater "width" is merely a perception from the lower aspect ratio of the tire making the tread look "bigger" compared to the sidewall. In fact, when I put my 245/45R17 stock tires (BFG KDWS) along side my new 245/40R18 toyos, the BFGs were almost 1/2" wider contact patch, simply because BFG's run big.

Now, TRAMS_AM, the second number the "40" of 245/40R18 is not 40mm. It's the aspect ratio, basically a percentage of the section width that represents the sidewall height - ie. 40% of 245 or 98mm. It's not exact, but what it means is that the sidewalls on a 245/45 is 5% higher than on a 245/40. So to address your comment, there is a sidewall difference between a 245/40 and 235/40, because it's 40% of 245 or 40% of 235. Subsequently, the 235/40 is shorter than the 245/40.

As for rubbing, what wheels are you planning to use?

[TRAMS_AM]

Now, TRAMS_AM, the second number the "40" of 245/40R18 is not 40mm. It's the aspect ratio, basically a percentage of the section width that represents the sidewall height - ie. 40% of 245 or 98mm. It's not exact, but what it means is that the sidewalls on a 245/45 is 5% higher than on a 245/40. So to address your comment, there is a sidewall difference between a 245/40 and 235/40, because it's 40% of 245 or 40% of 235. Subsequently, the 235/40 is shorter than the 245/40.

As for rubbing, what wheels are you planning to use?

You've turned my world upside-down! Okay, I've sat down and had a moment to reflect on this information.

I'm planning on using the 18"x8" HSV GTO V2 wheels (off the VY), and I believe the tire used on those is a 235/40/18. I'd like to use a 245/40/18, and think I can because several cars here are using that tire on the 18"x8" Monaro Series II wheel.

Also, you're the first person who's ever got my name right. Most call me 'Trans Am' and miss that first 'm'.

[miscreant]

You've turned my world upside-down! Okay, I've sat down and had a moment to reflect on this information.

I'm planning on using the 18"x8" HSV GTO V2 wheels (off the VY), and I believe the tire used on those is a 235/40/18. I'd like to use a 245/40/18, and think I can because several cars here are using that tire on the 18"x8" Monaro Series II wheel.

Also, you're the first person who's ever got my name right. Most call me 'Trans Am' and miss that first 'm'.
A couple people have had rubbing with certain tires in 245/40R18s. Once you select the tires, you might stop back here and get some feedback, as tires like Yokos, BFGs etc tend to run big and cause rubbing on the strut.

[TRAMS_AM]

A couple people have had rubbing with certain tires in 245/40R18s. Once you select the tires, you might stop back here and get some feedback, as tires like Yokos, BFGs etc tend to run big and cause rubbing on the strut.

It's between the Potenza S-03 (which some run in 235/40/18 without problems), the ECSTA MX (which I don't think anyone has), and the BFG KD (which GTPprix is running in a 245/40/18, but he's got spacers). I may just have to go for it.

[miscreant]

It's between the Potenza S-03 (which some run in 235/40/18 without problems), the ECSTA MX (which I don't think anyone has), and the BFG KD (which GTPprix is running in a 245/40/18, but he's got spacers). I may just have to go for it.
SO-3 should be fine, MXs should be fine, but the KD's will rub. The SO-3s are the best overall tire, but the MXs are VERY grippy!

[OldER Goat]

...SO-3 should be fine, MXs should be fine...

miscreant..are you saying you believe the 245s will be fine for the SO-3s and MXs (with the 48 mm OE 18" monaros) - or are you referring to the 235's in these particular tires ?

Trams Am..coincidentally these same tires are on my short list for the same wheels (18" HSV GTO). Im in the same boat..don't know which tires will work in 245 -other than the toyos (i assume most all will work in 235 size). have you made your selection yet ?? if so, any problems ? im also open to the pilot sports and the goodyears however.

im thinking of going with the 235 just to sure of clearance. im installing eibachs at the same time. do you think im giving up too much tire by going with the 235s vs 245 ? i gather the monaros are delivered with 235s ?

[miscreant]

miscreant..are you saying you believe the 245s will be fine for the SO-3s and MXs (with the 48 mm OE 18" monaros) - or are you referring to the 235's in these particular tires ?

Trams Am..coincidentally these same tires are on my short list for the same wheels (18" HSV GTO). Im in the same boat..don't know which tires will work in 245 -other than the toyos (i assume most all will work in 235 size). have you made your selection yet ?? if so, any problems ? im also open to the pilot sports and the goodyears however.

im thinking of going with the 235 just to sure of clearance. im installing eibachs at the same time. do you think im giving up too much tire by going with the 235s vs 245 ? i gather the monaros are delivered with 235s ?
I was talking the 245s.

"Should be" was honestly as far as I'd go ;) I just don't have direct experience with the actual size on that wheel, etc. I have owned both and at no time did I feel those two tires ran "big". This is one of those times where you almost want to talk you local tire guys down in price and get them to test fit...

[TRAMS_AM]

The HSV GTO wheels showed up today, and I'm about to order tires. I still am confident that a 245 will fit (aside from the KD, of course) as both the wheel calculator and other's experience says that the 245/40/18 won't run any bigger than the 245/45/17 that is currently on the car. I understand that it's pure theory and I should place more stock in what people are actually reporting, but since people are indeed running 245's without issue, I think I'm still going with that. I'll do a few more searches for the size and brand to see if there is anything that went unnoticed.

[TRAMS_AM]

Also, it appears that their 17"x8" rim gets 235/45/17's, so they may just run conservative all the time.

[TRAMS_AM]

LS1.com.au RE: 245's up front (http://www.ls1.com.au/forum/showthread.php?t=2135 0&highlight=245+tyre)

[TRAMS_AM]

But even after all that, it may be better to get a good, sticky tire in 235 than risk rubbing on a 245. Why is this such a difficult decision?!?

[miscreant]

But even after all that, it may be better to get a good, sticky tire in 235 than risk rubbing on a 245. Why is this such a difficult decision?!?
It's not that difficult, really. If it were me, I'd just get a good 245/40, something that I think might work and not something I know won't work (Like KDs or Pirellis), and then if there is a little rubbing, get some 5mm spacers for like $50.

[OldER Goat]

stranger and stranger...
robcorn is running the kdws (245x40) on 18x8 monaros (same offset as the hsv gto - i bet) and reports absolutely NO RUBBING issues whatsoever. like i said ..stranger and...

[miscreant]

stranger and stranger...
robcorn is running the kdws (245x40) on 18x8 monaros (same offset as the hsv gto - i bet) and reports absolutely NO RUBBING issues whatsoever. like i said ..stranger and...
KDWSs? I don't think they are WS's. I don't think BFG makes a 245/40 in the KWDS. They could be KDs or KDWs, but the KDs do run big. The KDWs are a little better in size. The section width on the stock KDWS is 9.6". The section width on the 245/40 KDWs is 9.6". The section width on the 245/40 KDs is 9.8". In comparison, the Pirelli Neros 245/40 section width is 9.8". The Toyo T1-S are 9.7" but also have a VERY round shoulder. The 245/40 MXs are 9.9" so they might be a little agressive, too. Etc., Etc... :)

EDIT: He's got KDs. Here's an interesting post though:

http://www.ls1gto.com/forums/showthread.php?t=1241 0&highlight=wheels

He's the only one that doesn't need spacers for some reason. The other guys running the same setup needed spacers.

[VYSHSV8]

245/40/18 so3's will fit due to a squarer shoulder on them so you shouldn't have any problems if you want to find out what HSV holdens racing car division is doing go to www.hsv.com.au and you can get the specs of 05 gto over here ls2's and evry other model hsv make

[TRAMS_AM]

These section widths are lifted from BF Goodrich's site:

KDW

235/40/18 9.5” on 8.5” (definitely safe)
245/40/18 9.6” on 8.5” (safe?)

KDWS

245/45/17 9.6” on 8” (rubs a little)

KD

245/40/18 9.8” on 8.5” (will rub)

Will putting a 245 KDW on a smaller rim cause it's section width to increase? If so, that would probably cause those to rub.

What say you?

[miscreant]

Will putting a 245 KDW on a smaller rim cause it's section width to increase? If so, that would probably cause those to rub.

What say you?
No, it would actually do the opposite. It would pull the sidewall in more, and reduce the section width a little, but can also square up the shoulder as well.

[SKPGTO4]

I PUT ON 245 40 WITH 18'S AND DID NO MODDING WITH THE FALKEN TIRES, i do get alittle rubbing in front of passenger tire,but its nothing to complain of really, i do wish someone made a 245 35 though!

[TRAMS_AM]

I PUT ON 245 40 WITH 18'S AND DID NO MODDING WITH THE FALKEN TIRES, i do get alittle rubbing in front of passenger tire,but its nothing to complain of really, i do wish someone made a 245 35 though!

You have aftermarket wheels, though. Do you know what offset they are?

[miscreant]

I PUT ON 245 40 WITH 18'S AND DID NO MODDING WITH THE FALKEN TIRES, i do get alittle rubbing in front of passenger tire,but its nothing to complain of really, i do wish someone made a 245 35 though!
But your's are aftermarket with different offsets. The wheels in question here are "stock" Australian wheels with the tight stock 48mm offset.
Alot of people make 245/35s, but those would be way too short, 1" shorter to be exact.