Plus Size Tires on Stock Wheels

[bewelch]

Has anyone had any experience with plus sizing tires on stock wheels on a 2002 vert. I will be replacing the run flats with conventional tires. The car has been lowered 1" all around. I want to keep stock wheels but fill up wheel wells and yes plus sizing will raise the car back up some. May also have to add spacers and wheel studs to move tires out a little............and no I do not want to go to 19 or 20 inch wheels. Stock tires are 245/45ZR17 and 275/40ZR18.

Please advise.

[froggy47]

Originally Posted by bewelch

Has anyone had any experience with plus sizing tires on stock wheels on a 2002 vert. I will be replacing the run flats with conventional tires. The car has been lowered 1" all around. I want to keep stock wheels but fill up wheel wells and yes plus sizing will raise the car back up some. May also have to add spacers and wheel studs to move tires out a little............and no I do not want to go to 19 or 20 inch wheels. Stock tires are 245/45ZR17 and 275/40ZR18.

Please advise.

Figure out the stock tire difference in height (or circumference) and stay very close to that difference with the new tire size, or your tc/ah will not be happy.

Also, you may find some tire dealers (like Costco for example) will only replace same size for same size.

:)

[rocket8189]

bewelch,

Here is my tire story, kinda long but may help. I have a '04 C5 Z06, fully lowered. It has Z16 stock GM wheels on it, those came off the commerative editon '03 C5 Z06 (Z16 RP0), the only bright wheel ever put on a C5 Z06 from the factory; they are polished aluminum, same style. Widths are 18/9.5 and 18/10.5. I wanted and did put PS2 Michelin Pilot Sports on it, would have loved 19 on the rear but didn't want to forsake the wheels. In fact, each time I talked to someone about going to a wheel that would give me 19 on rear, the vendor was more interested in buying my Z16 wheels than selling me their wheels; clearly decided to stay with my config.

I bought and had mounted 265/18 F and 295/18 R; I bought them from Tire Rack and asked the question on this forum about going to 315/18 rear, 295's already put me at fender's edge, don't really like wheel/tire combos outside the fender edge, but liked the look of more rubber under the beautiful butt.

C4C5 advised me--"The rear Z16 wheel will take a 315 but you will be outside the fender edge and more importantly you will be getting to the maximum width tire the wheel can handle. It will mount but there is a chance the outside edge of the tire will roll up due to maximum size for wheel and this could effect handling." Great advice and the kinda thing you always get here, good info.

So there you have it, I asked, got info and you can see where I went with fitment--by the way, I mounted the same size that came on those wheels/that unit from the factory, an oversized tire. By the way, pricey but love the PS2's; I'm a moderate driver, I wanted quiet running, smooth running, longer mileage tires and that's what I got. I'm an old guy and another reason is I knew I would not put another set on it so why not go first class.

Hope this helps.

Ken

[LLC5]

Originally Posted by rocket8189

bewelch,


C4C5 advised me--"The rear Z16 wheel will take a 315 but you will be outside the fender edge and more importantly you will be getting to the maximum width tire the wheel can handle. It will mount but there is a chance the outside edge of the tire will roll up due to maximum size for wheel and this could effect handling." Great advice and the kinda thing you always get here, good info.


Ken

On top of that issue, when you go to a plus sized tire for the wheel you can very easily run the center of the tire tread out a lot sooner than the inside and outside edges of the tire, and C5 rear tires don't need any help running the centers out of them.

[Fixvet]

Originally Posted by bewelch

Has anyone had any experience with plus sizing tires on stock wheels on a 2002 vert. I will be replacing the run flats with conventional tires. The car has been lowered 1" all around. I want to keep stock wheels but fill up wheel wells and yes plus sizing will raise the car back up some. May also have to add spacers and wheel studs to move tires out a little............and no I do not want to go to 19 or 20 inch wheels. Stock tires are 245/45ZR17 and 275/40ZR18.

Please advise.

TireRack's website has some Plus charts that might help.

[bewelch]

Ken,

Thanks much for your reply. I have plus sized every car I have owned. I know all the dimensions of the stock tires and the ones I want to put on it. The tires I want to use are 235/55ZR17 and 285/50ZR18/ In summary, I want to increase the rear tire diameter by 2 inches(actually will be 2.2 inches) which will raise the rear by 1.1 inches. The front tire dia will be increased by 1.6 inches which will raise the front .8 inches. The inside rear tire sidewall has 1" clearance to the inner fender panel. The 29.2 dia tire is .4 wider on a side than the stock tire and will be under the fender by .1 inch. The front tire is .2 wider on a side and the sidewall will stick out .013... probably not noticable and will depend on the dif in the measuring wheel size compared to the stock 8 1/2 wide wheel......but will not be much. However, I want the side walls of the tires to stick out by as much as 1/2 inch.....I like that look. I will probably get some hub centric spacers for the back and maybe the front if the turning radius does not hit the inner fender panels.

I have this exact combo on a muscle car with highly tuned suspension and am very pleased with it.

Also, on this forum, it has been stated that the rear tire/wheel MUST be .5 taller than the fronts or the TC/AH will be affected. They did not say how much over .5 you can go. I will check w/local Chev Dealer regarding this item.

Thanks for your input,
Bud

[Junkman]

Originally Posted by LLC5

On top of that issue, when you go to a plus sized tire for the wheel you can very easily run the center of the tire tread out a lot sooner than the inside and outside edges of the tire, and C5 rear tires don't need any help running the centers out of them.

lol! lol! lol!

[bewelch]

Ken,
I am trying to determine what range of tire diameters the AH/TC will accept without malfunction. I think I understand that the min rear dia must be is .5 inch in dia larger than the front. Do you know what the max is?
I asked a Chevrolet dealer service man today, who did a search on it in the GM database and could find nothing referencing AH/TC and tire size…………but that is just one service guy. You had referenced a 315/18 size that you were contemplating but a member advised that size may require a wider wheel, so I thought you may have stumbled on what the max dia can be w/o afftecting AH/TC.
Please advise,
Bud

[rocket8189]

Never got into AH/TC; once best tire size was supported by design/engineering advice, my search ended. Kinda would have liked bigger but risk was larger than advantage in my mind. I don't press my car and the Michelin PS2's have exceeded my expectations.

But, I have no doubt you will hit the limits successfully. Your working knowledge demonstrated here is impressive.

Ken