Wheel upgrade question.. 15" to 18"... problematic?

[jeffgrant]

Hello all-

Well, looks like I have to make a huge upgrade to my car. You see, it originally came with 15" BBS wheels, with a rear width of 11". Needless to say, I can't find ANY tires for the thing now, and so I have to upgrade my wheels/hubs.

So, after discussing this with my mechanic, and doing some soul searching and checking the couch for spare change, I'm thinking that I'd like to move to a Kinesis K18 wheel, while maintaining the 11" rear width.

My only real concern is I'm not sure what the additional stresses on the joints/bearings will be with the 18's, and if my '82 Turbo will be able to handle it all that well?

Anyone have any thoughts? (Or any other insights that I might be interested in?)

Anyone looking for 15" BBS 3-piece wheels, complete with the original BBS bolt-on wheel fans?


...jeff

[RickM]

Jeff: If you're looking to get 345-35-15 then call Damon at Tire Rack. He has several hundred Pirelli P-Zero Assymetricos on order with three left for delivery within the next couple/few weeks. After that you'll have to wait till early/mid May. You can order and won't be charged until they come in.

Apparently Pirelli is the only manufacturer making this size. These have not been discontinued.

They're $317 a pop....no pun intended.

Damon @TR 888-541 1777 ext 643

[Bill Verburg]

Modern sticky rubber will definitely put greater loads through all of the drive, suspension and brake components, but the difference between 15x11 and 18x11 won't present an insurmountable D

[jeffgrant]

Originally posted by RickM
Jeff: If you're looking to get 345-35-15 then call Damon at Tire Rack. He has several hundred Pirelli P-Zero Assymetricos on order with three left for delivery within the next couple/few weeks. After that you'll have to wait till early/mid May. You can order and won't be charged until they come in.

Apparently Pirelli is the only manufacturer making this size. These have not been discontinued.

They're $317 a pop....no pun intended.

Damon @TR 888-541 1777 ext 643

Thanks for the heads up! I looked at Tire Rack online, and they didn't list anything like that. In future, I guess I'll call them and talk to someone if I can't find what I'm looking for.

Also, talked to them, and they seem to be all spoken for until the next order comes in, in a few months.


So, I called Pirelli directly, and asked them about the tires. Seems that there's been enough interest in them that they are going to bring them back as a full-on, for public consumption tire. (Part #898600, if you're interested). They're supposed to be available to the public as of May, 2005.


All in all, seems to be good news, as I only have to spend (CDN) $1,500 for new tires instead of the $9,500 I was contemplating for new Kinesis K18's and new tires.


...jeff

[jeffgrant]

Originally posted by Bill Verburg
Modern sticky rubber will definitely put greater loads through all of the drive, suspension and brake components, but the difference between 15x11 and 18x11 won't present an insurmountable D

Thanks. Just out of curiosity, where do you think any problems with the extra load would manifest itself? Wheel Bearing failure?

[Bill Verburg]

I haven't really seen any issues in that area, usually, sway bar mounts, struts, brake mounts bushings etc. show accelerated wear.

[jeffgrant]

Great... All of that stuff is being replaced next week, so I should be OK. Thanks for the insight.


...jeff

[RarlyL8]

I just did the exact same thing.
Went from 9&12x15 Fuchs to 9&11x18 Roocks
LOVE THEM!
The lower profile 18" tires hold the road like glue! I gained 3" in rim height and only 1" in overall tire height.

Rear tires are not the immediate issue, I have a new set. It is the FRONT tires. Where are you getting them? Pirelli never made a 255/45-15 or a 285/40-15 to my knowledge. Those were the sizes I ran. 225/50-15s are WAY too skinny.

[RarlyL8]

FROM:



TO:

[jeffgrant]

Very nice! I am actually running 225/50/r15's on the front right now, and will continue to do so for a while yet, I think. This is what it came with, and I'm pretty happy with it right now... just the new rubber will be a HUGE difference. I've got old Yoko's on there right now...

The wheels that I want are just a little too pricey right now (Kinesis K18R's), as I'm outfitting a new stereo/gps system, larger intercooler, all new brakes, etc. I can't affort the additional $7k for the swap yet... maybe next month.


...jeff

[RarlyL8]

I'm going to sell the 18" tires shown above, if that helps.
They are 225/40-18 and 295/30-18 Pirelli P Zeros.

[jeffgrant]

Originally posted by RarlyL8
I'm going to sell the 18" tires shown above, if that helps.
They are 225/40-18 and 295/30-18 Pirelli P Zeros.

Thanks, but I wouldn't need them until after I buy the new wheels, and then I'm looking at a 345/35 rear tire anyway.

[RarlyL8]

Noone makes a 345/35-18 (which would be 27" tall !!). The largest 18" street tire I am aware of is a 315/30-18.

The 345/35-15 is period correct for a DP935. Awsome looking from the rear. The Fuchs pictured above have 345mm Yokos on the back. Previous to that I ran Pirellis. To my surprize the Yokos were 3/4" wider than the same size Pirellis. I had to buy new spacers to make them fit.

[strupgolf]

RarlyL8, I run the same Pirelli's on my car, and theylook great and I cant believe the way they hold the road. What offset do those wheels have and do you run spacers? How much do you want for the tires? I might buy them for backups. Thanks

[Bill Verburg]

Michelin and Pirelli both have a ~26" tall 335/30x18 which wants a 12" min rim width.

[RarlyL8]

The 18s require 1" front and 2" rear spacers.
I also am stunned by the grip.
The 295s went for $278 each at TireRack, the 225s are $180 each. The set is new. I have already replaced the fronts with 255s and plan to replace the rears with 315s. You can have the set of 4 for $600 free freight to your door.
You can e-mail me at RarlyL8@yahoo.com

Yes Bill, forgot about the altra-expensive 335/30-18 Rosso. Won't fit my rims and 26" is too tall.

(sorry to steal your thread Jeff)

[jeffgrant]

Originally posted by RarlyL8
Noone makes a 345/35-18 (which would be 27" tall !!). The largest 18" street tire I am aware of is a 315/30-18.

The 345/35-15 is period correct for a DP935. Awsome looking from the rear. The Fuchs pictured above have 345mm Yokos on the back. Previous to that I ran Pirellis. To my surprize the Yokos were 3/4" wider than the same size Pirellis. I had to buy new spacers to make them fit.

My mistake... I quoted what was on there now (at 15", not 18") by mistake. (I'm not really that up on tire/wheel lingo... but I seem to be learning fast!)

Mind you, what you've said worries me, as I now have those same Yoko's on my 15" BBS's, and am looking to move to Pirellis (as they seem to be the only ones that are making that size now). Just to be clear, are you saying that the Pirelli's were narrower than the same size Yoko's on 15" wheels?

Also, forgive my ignorance, but the spacers you're referring to... are they the outside pieces of the wheel that is attached by the 40+- bolts?

[RickM]

There were two tire manufacturers for the 345-35-15, Yokohama and Pirelli. At that time Pirelli offering was the P7. Then Yoko dropped their tire (as far as I know) and Pirelli moved on to the 1st generation P-Zero, then onto the P-Zero "system". The P-Zero has a slightly squared/wider shoulder (than the P7) so a lip roll or camber adjustment may be needed (Like for me). Kills you to see an expensive tire worn to the max on one side and brand new on the other....lol.

I think the reason Pirelli continues to make this side is because many Porsche wide body, Pantera and Countach cars use them.

FWIW, I also have 225/50VR15 on my fronts as well.

[RarlyL8]

The Yokos are wider than the Pirellis so you have no worries.
I'll post a picture for you this evening, I have a set of each in my garage.

The spacers are stock 930 units having longer studs that the spacer slides unto to space the wheel further from the hub. Adapters serve the same function but actually bolt onto the hub and the wheel then bolts onto the adapter. You end up with 10 lugnuts to attach one wheel.

[jeffgrant]

Originally posted by RarlyL8
The Yokos are wider than the Pirellis so you have no worries.
I'll post a picture for you this evening, I have a set of each in my garage.

The spacers are stock 930 units having longer studs that the spacer slides unto to space the wheel further from the hub. Adapters serve the same function but actually bolt onto the hub and the wheel then bolts onto the adapter. You end up with 10 lugnuts to attach one wheel.

Ahh... excellent. OK... that's what I'd always understood spacers to be... I've already got all that on the car right now, I just need to do a tire swap.

Thanks for the info!


...jeff