Wheel and Tire Info

[Justin]

Hey Guys,

Can someone tell me the bolt patterns and offsets that fit a 99 grand am gt?

Also what size 17, 18 and 19 rims and tires will fit it?

Thanks,

Justin

[Justin]

So no one knows?? LOL

[Artic]

I guess I can play wheel guru The 99+ is a bolt pattern of 5x115 or 5x114.3 with lugcentrics as far as the off set its usually a 38 although my enkeis are a 40 I have heard you can go to a max of 42.Tires and rims would be like this to keep the speedo right...
17- 225/45/17
18- 225/40/18
19- 225/35/19
If you wanna go lil wide with a 235 series speedo may be off a lil bit more.

[Justin]

Thanks so much man! I really appreciate it!

[Justin]

What does the offset mean?? what are the differences between 38-42?

[TA^Guy]

When shopping for wheels you might hear two terms, although messured differently are the same thing.

Offset and backsapcing are terms used to determine where the mounting surface of the wheel is.

Offset is messured from the center of the wheel. So 0 offset is center of the wheel. A wheel with a positive offset of 38mm means the mounting surface is 38mm off center towards the face of the wheel. When mounted this will move the wheel inward. A negitive offset will push the wheels out.
Photo shows a wheel with positive offset.

Backspacing is simular but messured from the backside of the wheel to the mounting surface in inches. The less inches the more the wheel will set out.

[Justin]

cool... so does it make a real big difference between 38 - 42 on looks?

[TA^Guy]

4mms you decide.

[Jason Lesbirel]

Originally posted by Justin
cool... so does it make a real big difference between 38 - 42 on looks?

4mm may not sound like a lot, but what isn't being considered is the clearancing of the suspension bits. The larger that number, the closer you move the inner edge of the rim to the strut and shock.

Now the rim itself may clear at 42mm, but put a tire on it, and depending on the size, the sidewall may come in contact with the suspension.

The clearance between the tire and strut body is very close in stock form - usually no more than the width of you typical finger, which is about 15mm (about 5/8 inch). Ideally you want to keep that the same, or if change is needed, increase that spacing, which means a smaller offset - 40 is smaller than 42, 38 is smaller than 40, you see where I'm going with that.

Besides, using a smaller offset increases the vehicle's track, which is a good thing.

[TA^Guy]

Jason, would you agree that wheels with larger offsets will put more wear on ball joints?
I know your a suspension guy and I have always felt it has. Just wonder what you think.

[Jason Lesbirel]

I would agree, but only if the offset change was drastic. Going from 38-40mm to 35mm would cause a negligible increase in wear on the ball joints.

Now, if you were to go to a 20mm offset, you'd be hanging the wheel way out. At that point, it's like putting a weight at the end of a diving board - the more weight you hang out from the pivot point (aka the balljoint), the more load put on it, and wear will naturally come sooner than expected.

[TA^Guy]

I agree, a few mm won't bother it much. But I always see custom truck with deep dish wheels all the way around and it makes me think how often they replace the ball joints. lol

[rollbonez]

So, with all of this in mind, what is the largest tire width I could put on an '02 GAGT if the offset of my rims are +38?

I am weighing different rim options and was looking at getting these with either a 235/40-18 tire or a 245/40-18 tire:

http://www.pfyc.com/store/merchant.m...ct_Code=GN9001

I am hoping to go wider primarily to get more contact patch, but more importantly to protect the rims when parallel parking and stuff!


tom

[Artic]

235 is as big as i would personal go

[Antalive[DM]]

Well see what is the stock rim width on 95's like 7.5
or 7.0 some thing like that (on tire i mean) The reason i ask is because i want more tread to hit the ground than what i got. So what kind of off set would i need for 8 inch width rims.

[silverbullet00]

[i]17- 225/45/17
18- 225/40/18
19- 225/35/19
[/B]

I used "Tire Size Comparator" and came up wit these figures and it would put the speedo right.

17" - 220/45/17 - Diameter difference is .06"
18" - 220/40/18 - Diameter difference is .07"
19" - 215/35/19 - Diameter difference is .07"

I used 225/60/16 as a stock tire to calculate these figures.

[rollbonez]

Originally posted by silverbullet00
I used "Tire Size Comparator" and came up wit these figures and it would put the speedo right.

17" - 220/45/17 - Diameter difference is .06"
18" - 220/40/18 - Diameter difference is .07"
19" - 215/35/19 - Diameter difference is .07"

I used 225/60/16 as a stock tire to calculate these figures.

Wouldn't you risk scraping the rims of the wheels if the tire wasn't wide enough to cover the rim?

That is my main concern... that if I get 18x8s compared to 18x7s, a 225mm wide tire might not protect my rims from the curb if I back up too far while parallel parking.

I could be wrong, but that inch seems like it would be a big difference to me.

tom

[Artic]

Well he is must be using the stock se size rollbonez.The largest you wanna go is the 235 that is the largest i have seen so far.

[master]

The OEM 16 x 6.5" wheels on the 1999+ cars, do you know what the offset is?

[92CamaroRS]

Originally posted by TA^Guy
I agree, a few mm won't bother it much. But I always see custom truck with deep dish wheels all the way around and it makes me think how often they replace the ball joints. lol

well seeing as this thread got brought back for the dead i figured id mention something.


next time you have a truck like that behind you look in your rearview and look at the tires. if they are toe'd out at the bottom their ball joints are shot. another thing that eats balljoints on trucks is driving around with the hubs locked in.