26.9" diameter tires, now Trac Cont lite comes on

[Thomas C Potter]

I have installed new wheels that have 26.9" dia tires, front and rear. (BFGoodrich says 27.1" in their specs, but tires are actually slightly less OD) All is grand except at about 30 mph the Traction Contriol light comes on with the related computer controlled reduction in power. I can bypass this by turning off the Trac Cont switch. I get no ABS fault. I know some folks have used 16" wheels with snow tires that I think are in the 26.7" diamter range.

My question is, is the traction control fully functional at less than 30 mph now?? Any other concerns??

TP in VA, Blue MM made in mid Jan '03.

[Thomas C Potter]

answer seems to be that yes the trac cont will work fine if fault light is off. But I am warned that if another issue arises, this could complicate or mask the other issue. Welcome to cars with fancy computers!!!

[nomad]

Can you post pictures,please?
Thank you.

[Thomas C Potter]

Nomad, I plan to post pictures as soon as it stops #$% raining and I can wash car and get good pictures. You can see the wheels at Colorado Custom, Empire III style. Or see ya at Ford Cralisle this weekend.

[Blue Marauder]

Why did you go with 16" rims and smaller tires?

[Thomas C Potter]

Blue Marauder, send me an email, I'll send pictures, to big to post. You need to activate your private email!!

17x8 Colorado Custom Wheels with BFG 255/50/17 KDWS Rev B 5/27/03

For those who are interested, I offer the following;

1) Backspace of these wheels are 7”, stock is 6.56”. 7” is needed so this 1.4” wider tire dose not rub the fender’s inner lip. This wider tire looks so much better than the weenie front 235 Mercury designed. I plan to lower car some in the future and want to have inner lip clearance and ability to set camber at 0 or -.25.
2) These BFG 255 are readily available and likely will be for years, the Impala SS and two other vehicles use them. Measured OD is 26.9 whereas MM front is 27.6. MM tires are unique and with MM being likely cancelled after 2004, who knows. Of course, other makes will likely be avail for the 18”.
3) Cost for 17” and these BFG are more reasonable than 18”. These wheels cost $350 each, tires $130 each. I like the BFG KDWS tires, MM stock feels good, and a friend modified his ’95 Impala SS suspension to handle better, and he still uses the KDWS 255’s and it feels great.
4) I’m using the same tire/wheel front and rear so I can rotate, I have to be practical on this car, a toy car is a different story. I may also buy 17x9 or 18x9 for a ‘summer’ rear set with 275.
5) I have now weighed and this combo is 56 lbs, stock MM front 52 lbs, rear 56. But, the rotational inertia of the assy is likely lower, which is better for braking and acceleration. (a 17” ring of metal has lower inertia than an 18” ring, same with tread) I plan to calculate one of these days.
6) Another possibility in the future for these 17” wheels are reasonable cost 255/45/17, but the smaller diameter may require a reprogramming of MM’s computer so ABS & Traction Control are properly functioning.
7) I was assuming the turn radius would be affected, but rack can still attain full travel.
8) You can see all the wheel styles that Colorado Custom offers at their website. I do not work for Col Cust, they are the only company I found who could make 7” backspace at a reasonable price, other were $720 or more!! I called a bunch of companies.
9) Original MM lug nuts work fine.
10) These smaller diameter tires also ‘improve’ the overall gearing, like installing 3.8 gears. Feels very good.
Now for some not so good info:
A) Most tire shops will -NOT- be able to mount tires on these Colorado fat lip wheels. The tire has to be put on from the backside (reverse mount), a little fact I found out the hard way!!! So, I am compelled to get a full size spare.
B) Valve stem is on the center part of wheel and a very short stem needs to be used, 1” maximum height from surface to clear caliper. No big deal.
C) The Traction Control light comes on at approx 30mph with the associated reduction in power caused by the computer. Simply turning off the switch on the dash solves this. I’m told by several car savy electrical engineers that this will not harm anything and that the traction control still functions if warning light has not activated. ABS warning light has not come-on.


- If you are looking for ANY aftermarket wheel, make sure it has the counterbores to clear the rotor mounting clips. These clips do perform a real function, that of keeping rotor in placed when wheel is removed, so dirt does not fall between rotor and hub. I’d recommend adding 1 or 2 more.

- If you are looking for ANY aftermarket wheel, make sure it has a 2.779” center bore so wheel is centered on hub. Careful of caliper clearance.

Some of you make balk at changing wheels thinking Mercury’s choice is gospel. I think 5 spoke wheels in general are boring!! The MM’s front tires are too narrow and the rears too tall.

If anyone is interested in having a serious conversation about wheels, send me your phone number in a private message.

TP in VA

[cruzer]

Traction Control senses the difference in the distance traveled by the front and rear wheels---changing the size (rotational speed ratio) causes activation of the control. Continental-Teves (the manufacturer) has a web site and they are excellent in replying to questions. I don't have a web address, but a search will find them

[cruzer]

Note :: a spinning wheel is sensed as actually moving forward at that speed

[Dennis Reinhart]

Originally posted by Thomas C Potter
I have installed new wheels that have 26.9" dia tires, front and rear. (BFGoodrich says 27.1" in their specs, but tires are actually slightly less OD) All is grand except at about 30 mph the Traction Contriol light comes on with the related computer controlled reduction in power. I can bypass this by turning off the Trac Cont switch. I get no ABS fault. I know some folks have used 16" wheels with snow tires that I think are in the 26.7" diamter range.

My question is, is the traction control fully functional at less than 30 mph now?? Any other concerns??

TP in VA, Blue MM made in mid Jan '03.


This is no problem I can corect this with the Chip call me if I can help