Wheel question

[strengthrehab]

Right now I have 19x8.5 and 19x10 wheels. At some point I want 18x10 but not in the budget. When I upgrade from my A/S tires to some decent 200-300 tread tires should I stay at 8.5 or go up to 19x10 on front?

I know the 8.5 isn't optimal, but I'm just starting out again after years off track. I'm working my way up through HPDE to eventually be signed off solo.

Should I just suck it up and get the 19x10's and then 275 or 285 rubber? Or stay staggered?

I would have gone 19x10 square, but 255's on a 10 inch rim would have been crazy and my tires were brand new when I changed wheels.

Sponsored

 

[FlowForm_Wheels]

Honestly if it was me, I would put some new tires on now, and I wouldn't worry about the 19x10's up front. Save what you would spend on the 19x10 and keep saving until you can get your dream set of 18x10's to use specifically for the track. In the long run you'll end up with wheels which weigh less, and an optimum tire set up!

 

[strengthrehab]

Honestly if it was me, I would put some new tires on now, and I wouldn't worry about the 19x10's up front. Save what you would spend on the 19x10 and keep saving until you can get your dream set of 18x10's to use specifically for the track. In the long run you'll end up with wheels which weigh less, and an optimum tire set up!

that is a good plan and one that has been mentioned a lot in other circles: "run what ya brung".

What is the widest tire to fit on 8.5?

 

[Norm Peterson]

255/40 is really the widest tire size that is "approved" for what I'll call 'unrestricted use' on 8.5" wide wheels.

I'll clarify the notion of 'unrestricted' to suggest that while you can get away with running wider sizes on 8.5" rims for such limited-duration situations as drag race runs, autocrossing, or very temporary street situations where you have no other option, street driving (and certainly your track driving) does not fit within any reasonable definition of "unrestricted" or "short duration". The main culprits are probably sidewall heat generation and fatigue effects - and that the location of the sidewall 'flex point' moves up/down the sidewall slightly in response to variations in wheel width away from "measuring".


Norm

 

[strengthrehab]

255/40 is really the widest tire size that is "approved" for what I'll call 'unrestricted use' on 8.5" wide wheels.

I'll clarify the notion of 'unrestricted' to suggest that while you can get away with running wider sizes on 8.5" rims for such limited-duration situations as drag race runs, autocrossing, or very temporary street situations where you have no other option, street driving (and certainly your track driving) does not fit within any reasonable definition of "unrestricted" or "short duration". The main culprits are probably sidewall heat generation and fatigue effects - and that the location of the sidewall 'flex point' moves up/down the sidewall slightly in response to variations in wheel width away from "measuring".


Norm

Which is the reason why I'll probably stay with that width. I still want 275's, though. 255 is so tiny.

Sigh.

 

[Grintch]

And 255 is the narrowest tire that is recommended for a 10" wheel. So they fit it just a well as they fit on a 8.5, most think that max wheel size for a given tire is actually the optimum fitment if the tire size is limited by the rules or other factors.

So I totally don't understand why you bought 8.5" front wheels. Actually I don't understand why anyone would buy 8.5" wheels for a car pushing two tons (or recommend them - I am looking at you, American Muscle).

But it's better to drive on the wrong wheels or tires than it is not to drive. Worst case you wear out those wrong tires fast and have a better reason to upgrade.

 

[Norm Peterson]

Actually I don't understand why anyone would buy 8.5" wheels for a car pushing two tons (or recommend them - I am looking at you, American Muscle).

Heh . . . earlier today I sent off a comment to AM on this very matter - and got a response apologizing and suggesting that it'll be looked into. We'll see if anything comes of it.***

But I do understand the bigger suppliers' conservatism/caution - separate from what their main customers are more apt to prefer, I'm sure they don't want to be fielding any more "my tires rub, so what are you going to do for me?" complaints than absolutely necessary. Tire Rack isn't any better, with many 18x8 wheels for sale back when the S197 GT came from Ford with 18x8.5's.



***All I asked for was to add further clarification to the last sentence in their catalog note along the lines of "or if the car is to be used in hard cornering activities such as autocross or road course driving. Forced induction cars that are cornered hard may require special attention".


Norm

 

[strengthrehab]

Guilty of AM and not asking the right questions regarding a 255 on a 10"wheel.

 

[Grintch]

Tire Rack USED to be good about telling you what would fit. Then they suddenly stopped and started only recommending near stock sizes.

Probably got sued when a large for the size tire on a offset not what the manfactuer claims wheel didn't fit.

 

[F0J]

Someone at Tire Rack called me to double check that I knew what I was doing.

Is there a book or online resource that describes the pros and cons of tire fitments for the track? In particular, putting a smaller than usual tire on a wider rim.

 

[Grintch]

Within the range that will fit on the car without significant modifications, wider is almost always better. This applies to both the wheel & tire.

If your tire size is limited by the rules or because you are just upgrading your wheels, use the widest recommended wheel for that tire size.

If your wheel size is limited by the rules or you just upgrading the tires, fit the widest recommended tire for that wheel size.

It's not unkown to push the limits a step or two beyond the recommended ranges. It was very common for Stock class autocrossers (limited wheel size) to fit tires 1 or 2 sizes be wider than the recommended range. I have also seen the odd racecar or autocross car running a 1 size wider wheel than recomeneded, but that is a lot less common (maybe because tire size limits are rarer than whell size limits?).

 

[strengthrehab]

I picked up a set of Forgestar 18x10 +42 for a great deal thanks to Black Friday. Saved over 400 dollars on the set. I'll get the tires next (MPSS 285-35-18).

 

[daltron]

I picked up a set of Forgestar 18x10 +42 for a great deal thanks to Black Friday. Saved over 400 dollars on the set. I'll get the tires next (MPSS 285-35-18).

Good man. When I was NA I went 19x10 squared and it made a ridiculous night and day improvement for handling. You are going to be quite happy. Ironically my my 19x10 square setup was MPSS as well :cheers:

Sponsored