tire size

[turnbull]

I have a 2004 Pontiac Sunfire with 225/45R17 tires. Due to the supercharger, the car has trouble keeping traction in 1st and 2nd gear. I want to get wider tires for better traction. The size I want to get is 255/40R17, which is about an inch wider than what I currently have.

My concern is the fitment of the tires. In addition to getting new tires, I also planned on getting new wheels to ensure the tires will fit, and also because I want to swap the heavy chrome wheels that it currently has to some lightweight alloys. I figured I could get new wheels with an offset that will allow the wider tires to fit.

Will I be able to run 255s if I get wheels with an offset? Any suggestions for good alloys for this car? I'd like them to be hub centric if possible. Thanks.

 

[melsg5]

the largest original equipment tire and wheel was 205/55x16 which is almost 25" in diameter. Your current 225/45x17 is almost an inch wider and is about the same diameter. The 255/40x17 increases your width a little more than an additional inch. You have to determine whether you have room for another inch beyond what you currently have by checking the clearances between the frame and the tire/wheel and the quarter panel and the tire/wheel. The link below was found by looking for "measuring tire clearance" and is one of many. I recommend you read them and follow their instructions to determine if your tire and wheel choice will fit.

http://www.superchevy.com/how-to/wh...ure-for-bigger-wheels-and-tires-size-matters/

 

[turnbull]

the largest original equipment tire and wheel was 205/55x16 which is almost 25" in diameter. Your current 225/45x17 is almost an inch wider and is about the same diameter. The 255/40x17 increases your width a little more than an additional inch. You have to determine whether you have room for another inch beyond what you currently have by checking the clearances between the frame and the tire/wheel and the quarter panel and the tire/wheel. The link below was found by looking for "measuring tire clearance" and is one of many. I recommend you read them and follow their instructions to determine if your tire and wheel choice will fit.

http://www.superchevy.com/how-to/wh...ure-for-bigger-wheels-and-tires-size-matters/

Thanks. That is good info. The only problem is that it doesn't address my main concern which is contact with the fender when the suspension is compressed. So just as a rule of thumb, is it generally safe for the tire to stick past the fender, or will that cause the tire to rub the fender when the suspension is compressed? I may just end up getting new tires of the same size.

 

[melsg5]

Unless you have some sort of bump stop system there is no way to guarantee the lip of the wheel opening isnt going to hit the tire. How much room is to the inside? If there is room you can shift the wheel offset to the inside.

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[turnbull]

Unless you have some sort of bump stop system there is no way to guarantee the lip of the wheel opening isnt going to hit the tire. How much room is to the inside? If there is room you can shift the wheel offset to the inside.

Thanks for the info. I am used to my Jeep where I can have the tires stick out past the fenders without rubbing. I'll check the inside to see if there is any room, but my guess is that there isn't if the tires on there are already wider than the stock tires. The previous owner might have figured out that these were the widest tires that would fit on the car.

I may just stick to the same size tire. That will save me money from having to buy new wheels, and I will be more confident that they will fit. It may not give me enough traction for 1st gear, but it might help with 2nd. The tires on there right now are all seasons and are starting to dry rot, so I think a brand new set of summer tires will make a big difference even if they are the same size.